OXY-ACETYLENE 
WELDING 


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OXY-ACETYLENE 
WELDING 


OX  Y- ACETYLENE 
WELDING 


A  COMPREHENSIVE  TREATISE  ON  THE  PRACTICE 
OF  WELDING  CAST  IRON,  MALLEABLE  IRON, 
STEEL,  COPPER,  BRASS,  BRONZE,  AND  ALUMINUM 
BY  THE  OXY-ACETYLENE  METHOD,  TOGETHER 
WITH  CONCISE  INFORMATION  ON  THE  EQUIPMENT 
REQUIRED  FOR  BOTH  WELDING  AND  CUTTING 
BY  THIS  PROCESS 


BY   S.   W.   CILLER,   M.E. 

MEMBER  INSTITUTE  OF  METALS 
MEMBER  AMERICAN  INSTITUTE  OF  METALS 


FIRST  EDITION 


NEW  YORK 

THE   INDUSTRIAL   PRESS 

LONDON:   THE   MACHINERY   PUBLISHING   CO.,   LTD. 
1916 


COPYRIGHT,  1916 

BY 

THE  INDUSTRIAL   PRESS 
NEW  YORK 


Composition  and  Electrotyping  by  THE  PLIMPTON  PRESS,  Norwood,  Mass. 


PREFACE 


TEN  years  ago  the  oxy-acetylene  method  of  welding  and  cut- 
ting metals  was  hardly  more  than  a  laboratory  process,  but  in 
the  course  of  these  few  years  it  has  become  one  of  the  most  im- 
portant of  the  methods  in  the  metal-working  industries.  It  has 
made  possible  the  making  of  repairs  of  broken  machine  parts  that 
previously  had  to  be  replaced  by  entirely  new  castings  or  forg- 
ings.  Not  only  has  the  process  proved  of  the  utmost  importance 
in  repair  work,  but  its  application  has  also  been  found  to  be  of 
the  greatest  value  in  the  manufacture  of  many  articles.  Much 
has  been  published  relating  to  this  process,  but  a  great  deal  of 
that  which  has  been  placed  on  record  in  the  past  has  been  de- 
scriptive of  odd  jobs.  It  is,  therefore,  believed  that  the  present 
volume,  dealing  in  a  more  systematic  manner  with  the  principles 
and  practice  of  the  art  of  oxy-acetylene  welding,  will  be  of  con- 
siderable value  to  those  engaged  in  the  metal  trades. 

The  information  here  presented  on  the  subjects  of  oxy-acety- 
lene welding  and  cutting  has  been  mainly  furnished  by  S.  W. 
Miller,  proprietor  of  the  Rochester  Welding  Works,  whose  wide 
experience  in  the  practical  application  of  the  process  and  whose 
success  in  the  work  vouch  for  the  reliability  of  the  information 
here  placed  on  record.  The  experience  of  the  author  in  the 
oxy-acetylene  welding  field  has  been  unusually  extensive,  but 
having  been  mostly  on  repair  work,  he  has  written  especially  for 
those  engaged  in  a  similar  line.  A  great  deal  of  the  work  done 
with  the  oxy-acetylene  welding  torch  is  on  repairs,  and  while 
there  are  also  a  great  many  applications  of  it  in  manufacturing 
work,  such  applications  are  more  or  less  special  in  each  case, 
and  sometimes  require  a  great  deal  of  experimenting  before 
success  is  attained.  The  general  principles  here  presented, 
however,  apply  equally  to  repair  and  manufacturing  work. 


358844 


VI  PREFACE 

In  the  publication  of  this  volume  the  Publishers  have  also 
made  use  of  several  articles  by  other  authors,  especially  articles 
by  Julius  Springer,  which  from  time  to  time  have  been  pub- 
lished in  MACHINERY.  A  chapter  on  "  Lead  Burning,"  by  James 
F.  Hobart,  has  also  been  included.  This  material  has  been 
added  in  order  to  give  as  complete  and  comprehensive  informa- 
tion as  possible.  In  general,  time  and  cost  data  have  purposely 
been  omitted  in  the  chapters  on  oxy-acetylene  welding,  because, 
in  the  present  state  of  the  art,  it  is  difficult,  if  not  impossible,  to 
give  accurate  cost  data  on  repair  work.  Two  welders,  working 
on  repairs  of  a  similar  character,  will  often  vary  as  much  as 
fifty  per  cent  in  the  time  consumed,  and,  as  shop  conditions  also 
vary  to  a  great  extent,  it  is  almost  impossible  to  give  accurate 
figures  regarding  cost. 

This  volume  describes  the  equipment  required  for  oxy-acety- 
lene welding  and  cutting,  deals  in  detail  with  the  methods  used 
for  welding  cast  iron,  malleable  iron,  steel,  copper,  brass,  bronze, 
and  aluminum,  and  gives,  in  addition,  special  attention  to  the 
welding  of  sheet  metal,  tank  welding,  boiler  repairs,  etc.,  as  well 
as  to  the  subject  of  lead  burning,  which  is  really  a  kind  of  autoge- 
nous welding.  All  of  the  information  given  has  been  obtained 
from  the  most  authoritative  sources,  the  descriptions  of  the  weld- 
ing apparatus  and  gas  generators  having  been  furnished  by  the 
manufacturers  in  each  case,  and  has  been  subjected  to  careful 
and  painstaking  editorial  work  by  the  staff  of  MACHINERY'S 
Book  Department,  by  whom  all  the  volumes  in  MACHINERY'S 
Mechanical  Library  have  been  prepared.  Hence,  the  Pub- 
lishers believe  that  the  present  volume  on  oxy-acetylene  welding 
and  cutting  equipment  and  practice  will  be  found  to  be  of  very 
great  value  in  the  metal-working  field. 

THE  PUBLISHERS. 

NEW  YORK,  July,  1916. 


AUTHOR'S   NOTE 

IN  preparing  these  chapters,  the  author  has  had  in  mind  his 
own  early  experience  in  oxy-acetylene  welding,  and  recognizes 
that,  at  best,  much  experimenting  must  be  done,  because  no 
descriptions,  however  complete,  can  fully  cover  all  the  small 
details  of  successful  welding  work;  but  the  author  has  endeav- 
ored to  cover  the  principles  that  are  of  general  value  and 
application.  He  believes  that  photographs  are,  in  most  cases, 
superior  to  long  descriptions,  and  has,  to  a  large  extent,  acted 
upon  this  belief.  All  of  the  photographs  shown  are  of  success- 
ful work  done  in  his  own  shops,  with  the  exception  of  less  than 
half  a  dozen,  which  were  added  by  the  publishers. 

The  author  knows  of  no  book  devoted  to  repair  work,  and 
although  descriptions  of  work  done  have  appeared  from  time 
to  time,  in  the  mechanical  papers,  they  do  not  appear  to  be  as 
complete  as  desirable,  and,  for  this  reason,  the  writing  of  this 
book  was  undertaken.  The  author  believes  that  equally  good 
results  may  be  obtained  in  other  ways  than  those  which  he 
describes;  but  all  methods  described  have  produced  thoroughly 
reliable  and  successful  results,  and  he  knows  that  what  he  has 
done  others  can  do  by  following  the  same  procedure.  Beginners, 
especially,  are  advised  to  avoid  apparent  short  cuts,  which  are 
liable  to  prove  costly  when  not  used  by  a  welder  of  judgment 
and  experience. 

The  metallurgical  side  of  oxy-acetylene  welding  is  of  great 
interest  and  importance,  but  it  has  not  as  yet  been  studied 
as  thoroughly  as  will  be  required  for  the  highest  development 
of  the  art.  In  the  chapters  that  follow,  however,  the  require- 
ments of  the  practical  man  have  been  kept  in  view,  and  the 


AUTHOR  S   NOTE 

theory  has  been  avoided  as  much  as  possible.  The  author 
hopes  that  the  information  imparted  will  prove  of  service  to 
those  engaged  in  the  art  of  oxy-acetylene  welding,  the  possi- 
bilities of  which  have  only  begun  to  be  developed. 

S.  W.  MILLER. 
ROCHESTER,  July,  1916. 


CONTENTS 

INTRODUCTION 

PAGES 

AUTOGENOUS  AND  FUSION  WELDING 

Fusion  Welding  —  Development  of  Oxy-acetylene  Welding 
Process  —  Application  of  the  Process 1-5 

CHAPTER  I 
EQUIPMENT  FOR  OXY-ACETYLENE  WELDING 

The    Welding    Torch  —  Cutting    Torches  —  Regulating 
Valves  —  Hydraulic   Safety  Valves  —  Adjusting  the  Weld- 
ing Torch  — Size  of  Torch  Tip  — Torch  Flame  Tempera- 
tures —  Care  of  Apparatus  —  Oxy-acetylene  Apparatus  — 
Methods    of    Producing    Oxygen  —  Liquid-air    Process  — 
Electrolytic  Process  —  Chlorate-of-potash   Process  —  Influ- 
ence of  Impurities  in  Oxygen  —  Acetylene  —  Acetone  for 
Storing  Acetylene  —  Precautions  in  the  Use  of  Acetylene 
Generators  —  Types    of    Generators  —  Impurities    in    Cal- 
cium   Carbide  —  Hydrogen  —  City    Gas     for    Welding  — 
Piping  —  Acetylene   and   Oxygen   Tanks  —  Machine   Tool 
Equipment  for -Welding  Shops  —  Miscellaneous  Shop  Equip- 
ment —  Plaster-of-paris  Patterns  —  Shop  Arrangement  — 
Fire  Risk  —  Eye  Protection 6-64 

CHAPTER  II 
PREPARATION  OF  WORK  FOR  WELDING 

Beveling  of  Edges  —  Welding  Pipe  Fittings  —  Welding 
without  Beveling  —  Handling  Heavy  Hot  Pieces  —  Align- 
ment —  Warping  or  Cracking  —  Setting-up  Work  for  Weld- 
ing —  Preheating  —  Charcoal  for  Preheating  —  Temporary 
Furnace  for  Preheating  —  Hood  used  for  Preheating  Opera- 
tions—  Preheating  Temperatures  —  Examples  of  Preheat- 
ing   65-82 


X  CONTENTS 

CHAPTER  III 
MATERIALS  AND   FLUXES   USED   FOR  WELDING 

Welding-rod  for  Cast  Iron  —  Welding- wire  for  Steel  — 
Welding  Material  for  Steel  Castings  —  Welding  Material  for 
Tool  Steel  —  Welding-rods  for  Copper  and  Copper  Alloys 
-  Welding  Material  for  Aluminum  —  Material  for  Welding 
Malleable  Iron  —  Fluxes  used  for  Oxy-acetylene  Welding  — 
Flux  for  Cast  Iron  —  Steel  and  Wrought  Iron  Flux  —  Copper 
Welds  —  Fluxes  for  Copper  Alloys  —  Flux  for  Aluminum  — 
Welding  Aluminum  without  a  Flux  —  Aluminum  Alloys  .  . .     83-102 

CHAPTER  IV 
MAKING  OXY-ACETYLENE  WELDS 

General  Rules  for  Welding  —  The  Oxy-acetylene  Flame  — 
The  Neutral  Flame 103-110 

CHAPTER  V 
OXY-ACETYLENE  WELDING  OF   CAST  IRON 

Making  the  Weld  —  Finishing  and  Testing  the  Weld  — 
General  Precautions  in  Welding  —  Defects  in  Cast-iron 
Welds  —  Examples  of  Cast-iron  Welds  —  Welding  a  Crank- 
case  —  Welding  a  Shaper  Rocker  Arm  —  Repairing  Cyl- 
inders —  Preheating  a  Cylinder  —  Defective  Welding  of 
Cylinders  —  Welding  a  Heating  Boiler  Casting  —  Distor- 
tion of  Castings  —  Repairing  a  Press  Frame  —  Difficulties 
with  Cast-iron  Welds  — Hard  Spots  —  Chilling  Effect  of 
Welding  Table  —  Expansion  and  Contraction  —  Practical 
Examples  of  Neutralizing  Contraction  Stresses  —  Saving 
Babbitt  Bearings  when  Welding  —  Providing  for  Proper 
Alignment  —  Punch-press  Repairs 111-161 

CHAPTER  VI 

WELDING  STEEL,  MALLEABLE  IRON,  COPPER, 
AND  COPPER  ALLOYS 

General  Procedure  in  Steel  Welding  —  Metallurgy  of  Iron 
and  Its  Relation  to  Welding  —  Difference  between  Cast 


CONTENTS  xi 

Iron,  Wrought  Iron,  and  Steel  —  Kinds  of  Steel  Generally 
Welded  —  Burning     Steel  —  Heat- treatment     of     Welded 
Steel  —  Welding    High-speed    Steel    to    Machine    Steel  — 
Welding  Cast  Iron  to  Steel  —  Welding  Steel  Castings  - 
Spots    in    Welding  —  Welding    Malleable    Iron  —  Welding 
Copper  —  Welding    Copper    to    Steel  —  Welding    Copper 
Alloys  —  Filling  Blow-holes 162-183 

CHAPTER  VII 
WELDING  ALUMINUM 

Flux  for  Aluminum  Welding  —  Welding  without  Flux  — 
Procedure  in  Welding  —  Character  of  Flame  —  Preheating 
-  Manipulation  of  Welding-rod  and  Torch  —  Welding 
Sheet  Aluminum  — Examples  of  Aluminum  Welding  —  Weld- 
ing Aluminum-zinc  Alloys  —  Repairing  an  Inlet  Manifold  — 
Replacing  Crankcase  Lugs  —  Repairing  a  Crankcase  —  Re- 
pairing a  Housing  —  Repairing  a  Transmission  Case  —  Re- 
pairing Badly  Damaged  Crankcase  —  Aluminum  Castings 
for  Repair  Work 184-211 

• 
CHAPTER  VIII 

SHEET  METAL,  BOILER,  PIPE,  AND  TUBE 
WELDING 

Warping  due  to  Heating  of  Plates  —  Welding  Thin  Sheet 
Steel  — Speed  of  Sheet  and  Plate  Welding  —  Welding 
Copper  and  Aluminum  Sheets  —  Welding  Heads  of  Tanks  — 
Boiler  Welding  —  Welding  Galvanized  Plates  and  Tin  Plate 
—  Manufacture  of  Tubing  by  Welding  —  Tube  Welding 
Machine  —  Tests  on  Welded  Tubing  —  Welding  of  Gas 
Pipes 212-227 

CHAPTER  IX 

OXY-ACETYLENE  WELDING  OF  TANKS 
AND  RETORTS 

Form  of  Joints  —  Welding  Tops  and  Bottoms  to  Cylin- 
drical Vessels  —  Example  of  Welding  —  Welding  of  House- 
hold Utensils  —  Joints  of  Household  Utensils  —  Design  of 
Work  for  Welding  —  Welded  Expansion  Pipe  — Welding 
in  Large  Tank  Construction 228-238 


Xll  CONTENTS 

CHAPTER  X 

GENERAL  CONSIDERATIONS  IN  OXY- 
ACETYLENE  WELDING 

Unusual  Difficulties  in  Welding  —  Qualifications  of  a 
Welder  —  Training  of  Welders  —  Wages  of  Welders  —  Rest 
Periods  Required  on  Large  Work  —  Cooling  the  Torch  Tips 

—  Care  of  Apparatus  —  Overhead  Cost  —  Commercial  Lim- 
itations of  Welding  Process  —  Precautions   in  Welding  — 
Tests  on  Strength  of  Welds  —  Ductility  of  Steel  Welds  - 
Strength  of  Welds  in  Nonferrous  Metals  —  Local  Hardening 

and  Casehardening  by  Oxy-acetylene  Flame 239-256 

CHAPTER  XI 
LEAD  BURNING 

General  Practice  of  Lead  Burning  —  Starting  the  Lead 
Weld  —  Lead  Burning  without  Beveling  —  Apparatus  used 
for  Lead  Burning  —  Hydrogen  Generator  —  Operation  of 

Generator  —  Modern  Lead-burning  Outfits 257-265 

• 

CHAPTER  XII 

CUTTING   METALS  WITH  THE  OXIDIZING 
FLAME 

Principle  of  Method  —  Cutting  Torch  —  Hand  and  Ma- 
chine Cutting  —  Cleaning  Work  to  be  Cut  —  Procedure  in 
Cutting  —  Thickness  of  Metal  that  can  be  Cut  —  Metals 
that  can  be  Cut  —  Different  Gases  Used  —  Cutting  Metal 
Under  Water  —  Examples  of  Metal  Cutting  —  Cost  of  Cut- 
ting Metal  with  the  Oxy-acetylene  and  Oxy-hydrogen  Flame 

—  Increasing  the  Efficiency  of  the  Cutting  Torch 266-279 

INDEX 281-287 


OXY-ACETYLENE  WELDING 


INTRODUCTION 
AUTOGENOUS   AND    FUSION   WELDING 

DURING  the  past  fifteen  years  several  valuable  processes  for 
joining  metal  parts  have  been  developed,  which,  to  a  consider- 
able extent,  have  taken  the  place  of  ordinary  forge  welding, 
soldering,  and  brazing,  which  latter  methods  are  very  old  and 
which  have  been  used  from  time  immemorial.  Not  only  have 
the  new  processes  that  have  been  developed  taken  the  place  of 
the  older  processes,  in  many  instances,  but  entirely  new  fields 
have  been  opened  up  for  the  application  of  welding,  and  to-day 
various  methods  of  welding  —  autogenous,  electric,  and  thermit 
—  are  applied  to  metals  under  conditions  where  the  ordinary 
forge  welding  process  would  be  wholly  inadequate. 

Forge  welding  is  applicable  only  to  the  joining  of  parts  of 
wrought  iron  and  low-carbon  steel.  It  is  true  that  high-carbon 
steel,  and  some  of  the  other  metals,  may  also  be  welded  by  this 
method,  but  these  welds  are  not  always  satisfactory  and  are 
never  as  strong  as  the  metal  itself.  Soldering  can  be  used  only 
on  small  light  work  for  joints  which  are  exposed  to  ordinary 
temperatures,  or  temperatures  only  slightly  above  the  boiling 
point  of  water,  the  reason  for  this  being  that  the  melting  point 
of  most  soldering  alloys  is  about  400  degrees  F.  Brazing,  that 
is,  the  joining  of  metal  parts  by  the  fusion  of  a  so-called  "  spelter 
solder,"  is  applicable  to  iron,  steel,  copper,  brass,  and  several 
other  metals,  but,  on  many  kinds  of  work,  the  process  is  rather 
uncertain  in  its  results,  even  when  in  the  hands  of  experts,  unless 
a  good  equipment  is  provided  for  controlling  the  heat  and  ma- 
nipulating the  work.  Because  of '  these  limitations  of  the  older 


2**«:  •<  '..*•  •  •-'ATJT0GENOT5S  AND   FUSION   WELDING 

processes,  the  newer  processes  have  had  a  very  rapid  develop- 
ment, and  have  within  comparatively  few  years  become  recog- 
nized as  among  the  most  important  of  the  methods  used  in  the 
metal-working  field.  The  three  most  important  of  these  new 
welding  methods  are  the  electric  welding  process,  the  thermit 
welding  process,  and  the  autogenous  welding  process,  the  latter 
of  which  is  dealt  with  in  the  following  chapters. 

Fusion  Welding.  —  Welding  is  understood  generally  to  mean 
the  uniting  of  two  pieces  of  iron  or  steel  by  heating  them  to  the 
temperature  at  which  they  become  softened  or  pasty,  without 
melting  them,  placing  them  together,  and  by  hammering,  or  in 
some  other  way,  bringing  them  into  intimate  contact.  As  is 
well  known,  this  cannot  be  done  with  any  of  the  common  metals 
except  wrought  iron  or  steel.  The  process  of  fusing  and  uniting 
metals  by  the  application  of  intense  heat  from  a  gas  flame  with- 
out compression  or  hammering  is  generally  known  as  "  autoge- 
nous welding."  The  temperature  required  is  obtained  by  the 
combustion  of  a  gas  containing  carbon  or  hydrogen,  or  both,  by 
the  aid  of  pure  oxygen.  Acetylene  is  the  gas  generally  used,  al- 
though hydrogen  is  also  employed.  The  gases  are  thoroughly 
mixed  in  a  torch  or  blowpipe  to  insure  perfect  combustion, 
which  takes  place  at  the  nozzle  or  tip.  A  modification  of  the 
welding  torch  is  also  utilized  for  the  cutting  of  iron  and  steel 
by  heating  and  burning  away  the  metal  by  oxidizing  it. 

The  word  "  autogenous,"  used  in  connection  with  the  name 
of  this  process  of  welding,  is  not,  however,  strictly  accurate. 
Autogenous  means  "  self  -produced,"  and  this  application  of 
the  word  is  not  descriptive  of  a  weld  made  by  the  oxy-acety- 
lene  process.  One  idea  that  should  be  conveyed  by  any  word 
describing  a  weld  of  this  kind  is  that  it  is  made  with  the  same 
kind  of  metal  as  that  of  which  the  piece  is  composed.  That  is, 
it  is  not  a  joining  or  soldering  process,  but,  strictly  speaking,  a 
welding  process.  The  word  "  autogenous,"  however,  does  not 
convey  this  meaning.  Another  idea  that  should  be  conveyed 
by  the  name  of  the  process  is  that  it  involves  the  melting  of  the 
metal  during  the  making  of  the  weld.  Probably  there  is  no 
word  which  conveys  all  of  the  ideas  involved,  but "  homogeneous" 


AUTOGENOUS  AND  FUSION  WELDING  3 

would  better  explain  the  uniformity  of  the  character  of  the  weld 
than  "  autogenous."  This,  however,  is  a  long  word  and  is  not 
especially  descriptive  of  the  process,  as  one  of  the  essential 
features  of  the  process  is  the  melting  of  the  metal,  and  hence 
it  would  seem  that  the  term  "  fusion  welding,"  which  is  short, 
descriptive,  and  distinctive,  should  be  entirely  satisfactory. 
However,  the  expression  "autogenous  welding"  has  become  a 
term  so  generally  used  that  it  seems  doubtful  if  any  other  ex- 
pression, even  though  more  expressive  and  definite,  will  ever 
replace  it. 

In  oxy-acetylene  welding  the  weld  may  be  formed  directly 
between  the  two  adjoining  surfaces,  but,  more  commonly,  it 
is  formed  by  fusing  in  additional  material  between  the  surfaces 
of  the  joint.  This  material  is  in  the  form  of  a  rod  or  wire,  and 
may  or  may  not  be  of  the  same  composition  as  the  material  being 
welded. 

Development  of  Oxy-acetylene  Welding  Process.  —  Autoge- 
nous welding  is  generally  spoken  of  as  a  modern  development, 
and  this,  of  course,  is  true  as  regards  its  present  commercial 
application.  As  a  matter  of  fact,  however,  it  is  known  that  the 
Romans  used  a  fusion  welding  method  for  the  joining  of  lead 
pipes  a  century  or  two  before  Christ.  As  they  had  no  knowledge, 
however,  of  producing  the  high  temperatures  required  for  the 
autogenous  welding  of  metals  having  a  high  melting  tempera- 
ture, the  early  application  of  the  fusion  welding  process  was 
limited  to  lead,  the  melting  point  of  which  is  about  620  degrees 
F.  The  process  of  autogenous  welding  by  means  of  the  oxy- 
acetylene  torch  or  blowpipe  dates  back  only  to  the  year  1900. 
About  that  time  the  process  had  its  inception  in  France,  the 
first  experimenter  being  Edmund  Fouche,  of  Paris,  who,  in  con- 
junction with  Picard,  devised  the  first  practical  oxy-acetylene 
welding  torch  in  1901,  and  who,  after  a  couple  of  years  of  ex- 
perimenting, succeeded  in  producing  a  commercially  successful 
apparatus. 

For  some  time,  however,  the  process  remained  more  or  less  of 
a  laboratory  method,  and  the  commercial  development  of  oxy- 
acetylene  welding  and  cutting  may  be  said  to  have  taken  place 


4  AUTOGENOUS  AND  FUSION  WELDING 

during  a  brief  period  beginning  about  1905.  Considering  the 
short  time  during  which  this  development  has  taken  place,  the 
process  has  reached  remarkably  high  perfection  and  efficiency. 
Apparatus  and  equipment  for  gas  welding  are  now  made  by  a 
number  of  manufacturers  in  the  United  States  and  Europe. 
The  principles  involved  in  the  use  of  the  apparatus  of  different 
makes  are  practically  the  same,  the  differences  being  mainly  in 
the  construction  of  the  torches  and  the  manner  in  which  the  gases 
are  generated.  Oxygen  and  acetylene  are  most  generally  used, 
although  oxygen  and  hydrogen  are  also  employed,  especially  in 
metal  cutting.  Great  difficulties  were  at  first  met  with  in 
cheaply  producing  pure  oxygen.  The  cheap  production  of 
acetylene  had  been  generally  solved  through  the  extensive  devel- 
opment of  acetylene  lighting;  but  the  means  for  generating  and 
storing  this  gas  have  also  been  further  developed  so  as  to  meet  all 
the  requirements  of  metal  welding  and  cutting  work.  Never- 
theless, while  these  advances  have  been  made,  the  cost  of  the 
gases  is  still  at  such  a  point  that  there  is  a  vast  amount  of  work 
that  cannot  be  done  by  the  oxy-acetylene  process,  which  will 
in  future  be  so  done,  when  the  cost  of  gases  is  still  further 
reduced. 

Application  of  the  Process.  —  The  oxy-acetylene  welding 
process  is  used  both  in  the  manufacture  of  articles,  the  parts  of 
which  would  otherwise  be  riveted  or  joined  by  other  means,  and 
in  repair  work.  In  both  fields  it  has  proved  to  be  of  exceptional 
value.  In  the  manufacture  of  many  articles  the  rapidity  with 
which  the  joints  can  be  made  and  the  comparatively  high  effi- 
ciency of  the  welds  make  it  of  great  importance ;  in  repair  work 
it  has  made  possible  the  saving  of  many  parts  which  otherwise 
would  have  to  be  thrown  away,  such  as  broken  automobile 
cylinder  castings,  crankcases,  and  parts  of  all  kinds  of  machin- 
ery. Some  special  applications  are  found  in  the  reclaiming  of 
cracked  castings  in  foundries,  the  filling  of  blow-holes  in  castings, 
the  adding  of  metal  to  worn  surfaces  to  secure  the  original 
thickness,  the  welding  of  piping  without  removal,  the  filling  of 
drilled  holes  that  have  been  incorrectly  located,  and  the  sealing 
of  riveted  seams  to  secure  absolutely  tight  joints,  which  cannot 


AUTOGENOUS   AND   FUSION   WELDING  5 

be  done  effectively  by  calking.  In  cutting,  the  blowpipe  is  used 
for  cutting  out  steel-plate  shapes,  cutting  holes  in  steel  plates, 
cutting  off  piping,  cutting  off  risers  from  steel  castings,  cutting 
structural  beams,  and  for  cutting  up  steel  wreckage,  etc. 

The  importance  of  the  autogenous  welding  process  for  produc- 
ing reliable  joints  in  thousands  of  manufactured  articles  which 
are  now  brazed,  riveted,  or  bolted  together  is  obvious.  In  many 
fields  the  process  has  revolutionized  past  manufacturing  methods, 
decreased  cost  of  production,  and  made  possible  the  placing  on 
the  market  of  articles  that  are  not  only  cheaper,  but  better,  more 
reliable,  or  more  convenient,  than  those  previously  made  by  other 
methods.  The  process,  of  course,  has  its  limitations,  as  will  be 
pointed  out  in  the  subsequent  chapters  of  this  treatise  on  oxy- 
acetylene  welding  and  cutting,  which  will  deal  in  detail  with  the 
equipment  used  for  producing  the  required  gases  and  for  perform 
ing  the  welding  operation,  the  preparation  of  the  stock  for  weld- 
ing, the  materials  used  for  filling  in  at  the  joints,  the  fluxes 
required  when  welding,  and  the  practice  followed  in  making  oxy- 
acetylene  welds  in  all  the  common  metals  to  which  the  process 
is  applicable. 


CHAPTER  I 
EQUIPMENT   FOR    OXY-ACETYLENE    WELDING 

THE  equipment  required  for  oxy-acetylene  welding  includes 
torches,  hose,  oxygen  and  acetylene  generators  and  containers, 
reducing  valves,  and  pressure  gages.  In  addition,  the  welding 
shop  must  be  provided  with  a  number  of  simple  machine  tools, 
special  tables  or  benches,  and  a  few  simple  appliances  or  jigs 
that  can  be  used  for  various  classes  of  work.  In  the  manu- 
facturing plant  where  oxy-acetylene  welding  is  used  extensively 
for  a  few  operations  continuously  repeated,  highly  developed 
special  tools  and  fixtures  are  employed.  Only  the  best  apparatus 
should  be  purchased,  and,  as  in  many  other  cases,  it  is  advis- 
able to  know  that  the  manufacturer  is  sound  financially  and  is 
going  to  continue  in  the  business.  The  patent  situation  with 
regard  to  welding  equipment,  and  even  in  regard  to  certain  pro- 
cesses, is  somewhat  confused  at  the  present  time,  and  it  is  well 
to  be  sure  that,  after  it  is  cleared  up,  repair  parts  can  be  obtained. 
The  manufacturers  of  the  best  apparatus  have  more  experience 
and  are  able  to  give  assistance  and  information  to  the  beginner 
which  is  not  obtainable  elsewhere.  Poor  apparatus  is  expensive 
to  operate  and,  therefore,  costly,  even  when  the  purchase  price 
may  appear  low. 

The  Welding  Torch.  —  The  first  practical  welding  torch  was 
devised  by  Fouche  and  Picard  in  France  in  1901,  and  the  first 
industrial  application  was  made  by  them  in  1903,  after  many 
experiments  to  avoid  the  danger  from  explosion.  It  was  also 
found  necessary  to  take  care  of  "  back-firing."  If  a  tube  of  com- 
paratively large  diameter  is  filled  with  a  mixture  of  gas  and  air, 
and  ignited  at  one  end,  the  flame  will  travel  to  the  other  end  at 
a  certain  speed,  depending  chiefly  upon  the  nature  of  the  gas, 
but  also  on  some  other  considerations,  such  as  the  size  of  the 

6 


WELDING  EQUIPMENT  7 

pipe.  It  has  been  found  that  it  is  necessary  to  have  a  very 
small  pipe  to  prevent  this  action  in  the  case  of  a  mixture  of 
acetylene  and  oxygen,  and  also  that  the  speed  of  travel  of  the 
flame  is  very  high  in  the  case  of  this  mixture.  The  dangers 
resulting  from  not  taking  proper  precautions  to  prevent  such 
flame-travel  are  well  illustrated  in  the  terrific  mine  explosions 
which  have  occurred  and  which  have  been  duplicated  in  experi- 
ments on  full-sized  tunnels  in  which  the  speed  of  travel  of  the 
flame  of  burning  mine  gases  has  been  accurately  measured. 
It  is  evident,  however,  that  if  the  mixture  of  gases  issues  from  the 
end  of  the  pipe  with  a  velocity  greater  than  that  with  which  the 
flame  travels  backward  in  the  pipe,  it  will  burn  without  any 
danger.  In  the  early  torches  with  comparatively  large  acetylene 
openings,  it  was  necessary  to  provide  a  chamber  in  the  torch  filled 
with  asbestos  and  provided  with  wire  gauze  partitions  to  prevent 
this  back-firing;  but  it  was  later  found  possible  to  do  away 
with  this  precaution,  if  the  acetylene  holes  in  the  head  of  the 
torch  were  made  sufficiently  small. 

Requirements  of  a  Good  Welding  Torch.  —  There  are  a  large 
number  of  torches  on  the  market,  some  of  which  are  good  and 
some  of  which  are  bad.  One  of  the  most  essential  features  of  a 
torch  is  the  use  of  as  little  oxygen  as  possible  in  proportion  to  the 
acetylene  used ;  early  torches  were  very  defective  in  this  respect. 
The  result  of  this  was  unsatisfactory  welds,  particularly  in  steel 
or  any  metal  which  is  easily  oxidized,  such  as  aluminum.  Mod- 
ern torches  give  much  better  results,  and  it  is  believed  that  still 
further  progress  will  be  made  in  the  future.  The  actual  amount 
of  oxygen  used  should  be  the  same  as  that  of  acetylene,  and  this 
is  quite  closely  approached  at  the  present  time  in  some  torches. 

Good  welding  can  be  done  with  any  good  torch;  as  stated, 
the  best  is  the  one  which  uses  the  least  oxygen  in  proportion  to 
acetylene,  because  it  is  less  expensive  in  operation  and  tends  to 
give  a  more  neutral  flame.  The  number  and  sizes  of  the  torches 
depend  upon  the  character  of  work  to  be  done,  but  there  should 
always  be  a  full  set  of  tips  provided.  If  this  is  not  done,  expe- 
rience proves  that  a  time  will  come  unexpectedly  when  a  tip  not 
on  hand  will  be  needed.  Hose  should  be  of  the  best  quality. 


8  WELDING  EQUIPMENT 

It  is  subject  to  quite  heavy  strains,  and,  as  the  lighter  the  torch 
is,  the  easier  it  is  to  handle,  the  best  quality  is  necessary  to  avoid 
excessive  wear. 

The  intensity  of  the  flame  from  an  oxy-acetylene  torch  is  the 
highest  that  can  be  produced  by  the  burning  of  gases.  It  is 
impossible  to  measure  the  temperature  directly,  but  from  theo- 
retical considerations  it  has  been  determined  that  it  is  about 
6300  degrees  F.  When  it  is  considered  that  the  melting  point  of 
cast  iron  is  about  2100  degrees  F.,  that  of  soft  steel  about  2600 
degrees  F.,  and  of  wrought  iron  about  2700  degrees  F.,  it  will  be 
seen  that  there  is  no  difficulty  whatever  in  melting  any  of  the 
metals. 

Types  of  Oxy-acetylene  Welding  Torches.  —  Leaving  aside 
those  torches  which'  use  acetylene  under  very  high  pressures, 
and  which  are  not  in  use  in  the  United  States,  all  torches  may  be 
divided  into  two  classes:  those  of  the  so-called  "injector"  type, 
in  which  the  acetylene  is  under  a  very  low  pressure,  say,  about 
six  ounces,  and  those  in  which  the  acetylene  pressure  is  con- 
siderably higher,  varying  from  one  to  six  pounds,  depending  upon 
the  size  of  the  tip.  These  latter  torches  are  generally  called 
"  medium-pressure "  torches.  The  pressures  referred  to  are 
those  given  on  the  gages  of  the  regulating  valves,  and  while  these 
pressures  have  to  be  used  by  the  welder,  to  regulate  the  flame 
of  the  torch,  they  are  not  the  pressures  that  really  produce  the 
gas  mixture.  These  latter  pressures  depend  entirely  upon  the 
dimensions  and  locations,  of  the  orifices  through  which  the  gases 
pass.  It  is  stated  at  times  that  a  certain  torch  of  a  certain  design 
is  an  "equal-pressure"  torch,  meaning  thereby  that  the  gage 
pressures  are  equal.  This,  however,  is  no  criterion  of  the  actual 
pressures  of  the  gases  at  the  work,  and  it  is  very  easy,  by  changing 
the  dimensions  of  the  passages,  to  change  any  torch  from  one  that 
uses  twice  as  much  oxygen  pressure  as  acetylene  pressure,  to  one 
using  equal  oxygen  and  acetylene  pressures,  or  even  less  oxygen 
pressure  than  acetylene  pressure,  all  of  the  pressures  referred  to 
being  those  shown  by  the  gages.  The  essential  difference,  there- 
fore, is  the  acetylene  pressure,  and  this  is  what  should  be  used 
as  a  classification  basis. 


WELDING  EQUIPMENT  g 

With  regard  to  the  pressures  as  shown  by  the  gages,  it  should 
be  mentioned  that  a  poor  gage  is  liable  to  produce  bad  results, 
and  it  is  a  fact  that  many  gages  do  not  register  correctly,  particu- 
larly at  the  low  pressures  at  which  the  acetylene  is  used;  so 
that,  if  the  gage  registers  incorrectly,  it  is  possible  to  obtain  too 
small  or  too  large  a  flame,  either  of  which  is  liable  to  give  bad 
results.  Pressure  gages  should,  therefore,  be  tested  at  intervals 


Machinery 


Fig.    1.     Tip     of     So-called 
"  Positive-pressure  "  Torch 


Fig.  2.   Tip  of  Low-pressure 
Torch 


and  adjusted,  so  that  they  will  give  as  close  results  as  possible 
over  the  range  in  which  they  are  used. 

Low-pressure  Torches.  — The  low-pressure  torch  works  on 
the  injector  principle,  the  oxygen  being  under  high  pressure,  so 
that  it  flows  rapidly  through  the  duct  in  the  head  of  the  torch 
and  draws  in  the  acetylene.  As  the  two  gases  flow  through  the 
duct  or  mixing  chamber  in  the  head  or  burner  tip,  they  are 
mixed  together  ready  for  combustion  to  take  place  as  they  emerge 
from  the  orifice  at  the  end  of  the  tip. 


1 


WELDING   EQUIPMENT  H 

Medium-pressure  Torches.  —  The  term  " medium-pressure'* 
is  employed  to  distinguish  torches  of  this  type  from  the  high- 
pressure  torches  which  were  used  in  France  at  the  time  that  the 
oxy-acetylene  welding  and  cutting  industry  was  in  the  early  stages 
of  its  development.  This  name  also  distinguishes  the  medium- 
pressure  torch  from  the  low-pressure  torch  in  which  the  acety- 
lene is  delivered  at  slightly  above  atmospheric  pressure. 

In  the  medium-pressure  torch,  both  gases  are  under  consider- 
able pressure,  so  that  the  flow  of  acetylene  does  not  depend 
upon  the  injector  principle.  It  will  be  noted  that,  in  both  types 
of  torches,  the  oxygen  and  acetylene  travel  through  a  duct  of 
considerable  length,  so  that  a  complete  mixture  is  obtained 
by  the  time  the  orifice  at  the  tip  is  reached.  Figs,  i  and  2 
illustrate  medium-  and  low-pressure  torches. 

Commercial  Designs  of  Torches.  —  Figs,  i  and  3  show  the 
design  of  welding  torch  which  has  been  adopted  as  a  standard 
construction  by  the  Davis-Bournonville  Co.  This  torch  is  made 
in  different  sizes  to  meet  the  requirements  of  various  classes  of 
work.  One  of  the  basic  principles  of  this  type  of  torch  —  which 
was  covered  in  the  original  French  patent  and  also  by  patents 
in  the  United  States  —  provides  for  using  different  sizes  of  inter- 
changeable burner  tips  in  a  given  size  of  torch,  in  order  to  adapt 
it  for  handling  various  kinds  of  work.  The  gases  enter  the  tip 
at  separate  points,  and  the  pressure  of  each  gas  is  regulated  to 
obtain  exactly  the  required  mixture.  Each  tip  provides  a  size 
of  flame  suitable  for  various  classes  of  work.  In  this  connection, 
it  is  interesting  to  note  that  a  patented  construction  has  been 
employed  for  fitting  the  burner  tip  into  the  head  of  the  torch. 
Instead  of  using  a  threaded  joint,  it  will  be  noted  that  the  tip 
is  tapered  at  A  to  fit  a  tapered  socket  in  the  head  of  the  torch. 
This  does  away  with  trouble  from  damaged  threads  which  re- 
sulted from  the  earlier  construction  in  which  the  tip  was  screwed 
into  the  head;  and  leakage  caused  by  expansion  or  contraction 
of  the  different  parts  of  the  torch  due  to  variations  in  the  tempera- 
ture has  been  done  away  with.  It  will,  of  course,  be  evident 
that  the  tip  is  held  in  place  in  the  head  of  the  torch  by  the  nut 
£,  and  that  the  oxygen  enters  the  tip  through  the  axial  duct, 


12  WELDING  EQUIPMENT 

while  the  acetylene  enters  the  groove  C  which  leads  the  gas  to 
the  four  ports  or  transverse  ducts  in  the  tip. 

Each  of  the  two  sizes  in  which  this  torch  is  made  is  provided 
with  five  different  sizes  of  tips.  The  five  smaller  sizes  provide 
for  welding  metal  from  ^V  up  to  J  inch  in  thickness,  while  the  five 
larger  sizes  are  employed  for  heavy  welding  operations  on  metal 
from  J  inch  in  thickness  and  up.  When  using  each  size  of  tip, 
a  definite  specified  pressure  of  the  oxygen  and  acetylene  is 
secured  through  the  use  of  pressure  regulators.  The  pressure  of 
the  oxygen  and  the  size  of  the  axial  duct  in  the  tip  bear  such  a 
relation  to  the  pressure  of  the  acetylene  and  the  size  of  the 
ports  or  transverse  ducts  that  the  ratio  between  the  consump- 
tion of  oxygen  and  acetylene  is  1.14  to  i,  which  gives  a  neutral 
flame. 

Fig.  2  shows  a  cross-section  of  the  welding  head  of  the  Oxweld 
low-pressure  or  injector  type  of  torch,  as  made  by  the  Oxweld 
Acetylene  Co.  The  notation  in  the  illustration  shows  the  con- 
struction clearly.  Fig.  4  shows  a  type  of  torch  which  differs 
in  its  arrangement  to  a  considerable  extent  from  the  other  two 
types  shown.  This  is  made  by  the  Prest-O-Lite  Co.  This 
torch  is  used  for  compressed  or  medium-pressure  acetylene  only, 
and,  therefore,  no  injector  device  is  necessary.  The  gases  mix 
near  the  handle,  and  flow  together  along  the  full  length  of  the 
stem.  The  handle  of  the  torch  is  fitted  with  "  anti-back-fire " 
chambers  for  both  gases,  filled  with  material  through  which  it 
is  impossible  for  the  flame  to  pass. 

Cutting  Torches.  —  In  cutting  iron  and  steel  with  the  oxy- 
acetylene  torch,  the  cut  is  made  by  the  burning  away  of  the  metal 
along  the  line  on  which  the  cut  is  to  be  made.  In  order  to  under- 
stand the  operation  of  the  cutting  torch,  the  reader  must  first 
grasp  the  idea  that  the  burning  of  any  matter  —  regardless  of 
whether  it  is  coal,  oil,  wood,  or  metal  —  is  due  to  the  chemical 
combination  of  the  oxygen  with  the  material  which  is  being 
burned.  In  the  case  of  iron  and  steel  this  burning  action  can 
only  take  place  at  very  high  temperatures,  and  for  this  reason 
the  metal  is  heated  by  means  of  the  oxy-acetylene  flame,  which 
raises  its  temperature  to  a  point  where  the  metal  will  combine 


WELDING  EQUIPMENT  13 

with  the  oxygen;  but  ordinary  air  consists  of  one  part  of  oxygen 
to  four  parts  of  nitrogen,  and  as  a  result  the  cutting  action  would 
be  quite  slow  if  additional  oxygen  were  not  supplied.  In  the 
early  forms  of  cutting  torches  this  was  done  by  attaching  a 
separate  tip  at  the  side  of  the  welding  torch,  which  was  connected 
to  a  third  tube  that  carried  an  auxiliary  supply  of  oxygen  and 
discharged  it  against  the  heated  metal.  The  flow  of  oxygen 
through  this  auxiliary  tip  was  controlled  by  means  of  a  valve 
which  was  held  open  by  depressing  a  thumb-lever. 

To  avoid  the  use  of  this  construction,  and  to  provide  a  cutting 
torch  on  which  only  two  hose  connections  are  required,  the 
Davis-Bournonville  Co.  is  now  manufacturing  a  torch  of  the  form 
shown  in  Fig.  5.  In  this  torch  there  are  two  rubber  tubes  which 
connect  the  torch  with  the  supply  6f  oxygen  and  acetylene. 
The  torch  itself  is  provided  with  three  metal  tubes,  A,  B,  and  C, 
and  the  tip  is  drilled  with  three  longitudinal  ducts,  D,  E,  and  F. 
Each  of  the  ducts  D  and  E  delivers  a  mixed  supply  of  oxygen 
and  acetylene  which  burns  at  the  tip  of  the  burner,  serving  to 
heat  the  metal  to  the  oxidizing  temperature.  So  far  as  the 
method  of  effecting  the  mixture  of  the  oxygen  and  acetylene  is 
concerned,  each  of  the  ducts  D  and  E  is  analogous  to  the  ducts 
of  the  welding  tip  which  has  already  been  described.  The  central 
duct  F  delivers  a  supply  of  pure  oxygen  to  the  metal  when  the 
thumb-lever  G  is  thrown  over  to  open  the  valve  in  tube  A  to  the 
oxygen  supply.  This  pure  oxygen  strikes  the  metal  which  has 
been  heated  to  a  high  temperature  by  the  oxy-acetylene  flame 
and  causes  a  rapid  oxidation  or  burning  of  the  metal  to  take  place. 
In  this  way  the  metal  is  burned  away  along  the  line  of  the  cut, 
but  with  a  narrow  saw-like  kerf  which,  when  the  cutting  is  skill- 
fully .done,  does  not  give  the  metal  the  appearance  of  having 
been  burned  or  melted.  The  torch  is  made  with  three  sizes  of 
interchangeable  tips  for  cutting  different  thicknesses  of  metal. 
The  smallest  tip  cuts  metal  from  \  to  f  inch  in  thickness,  the 
medium  tip  from  i  to  3  inches  in  thickness,  and  the  largest  size 
from  3  inches  in  thickness  up.  As  in  the  case  of  the  welding  tips, 
each  size  of  cutting  tip  uses  the  oxygen  and  acetylene  under 
specified  pressures. 


WELDING  EQUIPMENT 


Examples  of  Torches  for  Different  Purposes.  —  Fig.  7  shows 
a  group  of  the  different  styles  of  welding  and  cutting  torches 
manufactured  by  the  Davis-Bournonville  Co.  A  large  size  of 


Machinery 


Fig.  7.   Different  Types  of  Cutting  and  Welding  Torches 

welding  torch  is  shown  at  A,  this  being  a  standard  torch  for 
performing  medium  and  heavy  welding  operations  in  making 
boiler  repairs,  and  for  general  shop  work.  The  torch  is  fitted 
with  a  set  of  the  five  large-sized  welding  tips,  and  is  adapted  for 


1 6  WELDING  EQUIPMENT 

welding  metal  from  -f-Q  inch  in  thickness  up.  It  is  20  inches  long 
and  weighs  2  pounds.  A  special  torch  of  this  size  is  made  in  a 
3 -foot  length  for  very  heavy  work  where  it  is  desirable  to  enable 
the  operator  to  get  as  far  away  from  the  work  as  possible,  owing, 
to  discomfort  experienced  from  the  intense  temperature  of  the 
metal.  The  standard  two-hose  cutting  torch  is  shown  at  B. 
This  torch  is  20  inches  long  and  weighs  40  ounces.  What  is 
known  as  a  "  manufacturers "  torch  is  shown  at  C.  This  torch 
meets  the  requirements  for  light  and  medium  sheet-metal  welding; 
it  is  especially  adapted  for  manufacturing  operations  on  boilers, 
steel  barrels,  iron  and  steel  tanks,  cylinders,  etc.  A  small  size 
of  the  standard  welding  torch  is  shown  at  D,  this  torch  being 
convenient  for  use  on  light  and  medium  sheet-metal  welding 
and  on  light  repair  work.  It  is  14  inches  in  length  and  weighs 


Machinery 


Fig.  8.   Oxweld  Cutting  Torch 

1 8  ounces.  This  torch  is  provided  with  a  set  of  the  five  small- 
sized  tips  and  is  adapted  for  welding  metal  from  ^V  to  ^V  inch  in 
thickness.  A  torch  for  circular  hand  cutting  is  shown  at  E. 
This  torch  is  of  the  same  general  type  as  the  standard  cutting 
torch,  but  is  fitted  with  a  compass  attachment  to  adapt  it  for 
cutting  circular  holes.  Torches  for  use  on  cutting  and  welding 
machines  are  shown  at  F  and  G,  and  a  torch  with  water-cooled 
head  and  tips  at  H.  This  type  is  for  use  on  heavy  welding 
where  there  is  a  tendency  for  the  head  and  tip  of  the  torch  to 
become  overheated  from  the  intense  heat  radiated  by  the  metal 
.that  is  being  operated  upon.  This  is  especially  true  in  cases 
where  the  head  of  the  torch  is  surrounded  by  the  heated  metal, 
and,  to  overcome  this  difficulty,  a  supply  of  cooling  water  is 
circulated  through  the  head  and  tip  by  means  of  two  extra  hose 
connections  provided  for  the  purpose.  At  7  is  shown  an  oxy- 


WELDING  EQUIPMENT 


hydrogen  cutting  torch  in  which  hydrogen  gas  is  burned  in  place 
of  acetylene. 

In  Fig.  8  is  shown  the  Oxweld  cutting  torch,  which  differs 
from  the  welding  torch  made  by  trie  same  concern  mainly  in  that 
an  additional  oxygen  duct  is  provided. 

British  Cutting  Torch.  —  The  cutting  torch  most  generally 
used  in  Great  Britain  is  that  known  as  the  "  Universal,"  and  is 
made  by  the  British  Oxygen  Co.  This  company  has  acquired 
from  L'Oxhydrique  Internationale  a  patent  which  gives  it  exclu- 
sive rights  for  any  form  of  torch  which  employs  a  separate  jet  of 
oxygen  for  cutting  purposes. 


Machinery 


Fig.  9.  British  Type  of  Cutting  Blowpipe 

The  torch,  on  which  only  two  flexible  tubes  are  required,  is 
shown  in  Fig.  9.  The  oxygen  for  heating  and  cutting  enters  at 
A.  Acetylene  gas  from  a  generator  or  an  acetylene  cylinder 
enters  at  B.  The  oxygen  is  distributed  at  C,  the  cutting  oxygen 
being  controlled  by  a  valve  at  D,  and  the  heating  oxygen  by  a 
valve  at  E.  The  gases  for  heating  are  mixed  in  the  annular  pas- 
sage F,  and,  burning  at  the  nozzle,  serve  to  heat  the  metal  to  the 
cutting  temperature.  So  far  as  the  method  of  effecting  the  mix- 
ture of  the  oxygen  and  acetylene  is  concerned,  it  is  analogous  to 
that  of  the  welding  torch.  The  central  passage  delivers  a  supply 


i8 


WELDING   EQUIPMENT 


of  pure  oxygen  to  the  metal  when  the  thumb-valve  D  is  opened. 
This  valve  is  capable  of  double  control,  as  it  can  be  operated  by 
the  hand  lever  G.  The  pure  oxygen  strikes  the  metal,  which  has 
been  heated  to  a  high  temperature  by  the  oxy-acetylene  flame, 
and  causes  rapid  oxidation  to  take  place.  In  this  way  the 
metal  is  removed  from  along  the  line  of  the  cut,  leaving  a  narrow 
saw-like  cut  which,  if  the  cutting  has  been  skillfully  done,  does 
not  give  the  metal  the  appearance  of  having  been  burned  or 
melted.  The  torches  are  made  with  five  different  sizes  of  cut- 


hlGH  PRESSURE 
GAGE  CONNECTION 


RELIEF  VALVE 


Machinery 


Fig.  10.   Diagrammatic  Section  of  Oxygen  Welding  Regulator  made  by 
the  Oxweld  Acetylene  Co. 

ting  nozzles  for  cutting  different  thicknesses  of  metal.  The 
smallest  tip  cuts  metal  from  J  to  f  inch  in  thickness,  the  next 
size  cuts  metal  from  i  to  6  inches  in  thickness,  the  next  from  6f 
to  9  inches,  the  next  from  Q|  to  14,  and  the  last,  17  inches  in 
thickness.  As  in  the  case  of  welding  torches,  each  thickness  to 
be  cut  uses  the  oxygen  under  specified  pressure. 

Regulating  Valves.  —  Regulating  valves  should  be  kept  in 
good  condition.  Unless  this  is  done,  so 'that  the  reduced  pres- 
sure remains  constant  under  all  conditions,  the  action  of  the 


WELDING  EQUIPMENT  ig 

torch  will  be  irregular  and  unsatisfactory.  In  the  course  of  time 
the  diaphragms  become  buckled  and  have  to  be  renewed.  This 
and  dirt  in  the  small  passages  are  the  only  difficulties  in  a  well- 
designed  valve.  Gages  and  regulating  valves  should  be  suitable 
for  the  work  and  of  substantial  design.  The  gage  capacity 
should  be  about  one  and  one-half  .times  the  maximum  pressure 
used.  The  gages  for  welding- torch  pressures  should  be  gradu- 
ated in  single  pounds,  and  need  not  have  over  50  pounds  ca- 
pacity. For  cutting  torches,  the  gages  should  .be  graduated  to 
about  250  pounds.  Good  gages  give  practically  no  trouble. 

Fig.  10  shows  a  section  of  the  Oxweld  Acetylene  Co.'s  oxy- 
gen welding  regulator  which  reduces  the  oxygen  tank  pressure, 
about  1800  pounds,  to  that  necessary  for  welding,  as  the  latter 
pressure  does  not  exceed  from  10  to  30  pounds.  Its  action 
is  as  follows:  the  oxygen  enters  from  the  tank  through  passage 
E  to  valve  F,  the  seat  for  which  is  held  away  from  the  valve  by 
the  spring  K  acting  through  the  diaphragm  C,  which  can  be 
adjusted  by  turning  handle  H,  to  obtain  any  desired  pressure. 
The  oxygen  then  passes  into  chamber  D,  and  when  there  is  suffi- 
cient pressure,  the  diaphragm  is  forced  to  the  left,  allowing  the 
small  spring  M  to  pull  the  valve  seat  against  the  valve  and  shut 
off  the  supply  of  oxygen.  As  soon  as  the  pressure  falls,  the  action 
is  reversed,  and  the  supply  of  oxygen  is  renewed.  The  oxygen 
passes  from  the  chamber  D,  through  a  connection  not  shown, 
to  the  hose.  The  regulator  for  cutting  is  similar  in  design  to 
that  for  welding,  but  as  the  cutting  pressure  may  run  up  to  100 
pounds,  it  is  made  heavier,  and  provides  for  a  larger  flow  of  gas. 
The  differences  in  conditions  make  it  necessary  to  use  different 
regulators  for  welding  and  cutting,  and  good  results  will  not 
be  obtained  unless  the  proper  regulator  is  used. 

Hydraulic  Safety  Valves.  —  An  essential  detail  for  low-pres- 
sure welding  and  cutting  installations  is  some  form  of  safety 
valve.  The  personal  safety  of  the  operator  and  the  protection 
of  the  piping  and  generating  plant  make  it  indispensable.  Its 
function  is  to  divert  any  oxygen  traveling  along  the  acetylene 
tube,  due  to  disturbance  in  the  torch  or  any  other  cause,  and 
to  extinguish  any  explosion  wave  reaching  the  valve.  Many 


20 


WELDING  EQUIPMENT 


devices  have  been  tried,  and  experience  shows  that  the  only 
reliable  device  is  some  form  of  water  valve.  A  common  form 
is  shown  in  Fig.  1 1 .  The  acetylene  gas  enters  at  A  and  bubbles 
through  the  small  holes  at  the  lower  end  of  the  inlet  tube.  The 
gas  leaves  the  body  of  the  valve  B  by  the  valve  H,  the  flexible 
tube  connecting  the  valve  and  the  torch  being  attached  at  C. 

The  water  level  is  fixed  by 
the  cock  F.  A  branch  tube 
D  with  a  funnel  E  open  to 
the  atmosphere,  or  closed 
with  a  loose  cover,  is  at- 
tached practically  midway 
between  the  level  of  the 
water  given  by  F  and  the 
level  of  the  upper -exit  holes 
in  the  inlet  tube.  The  figure 
shows  the  valve  in  the  work- 
ing position,  the  cocks  G  and 
H  being  open  and  the  cock 
F  closed.  In  the  event  of 
the  oxygen  traveling  along 
the  acetylene  tube,  or  the 
return  of  an  explosion  wave, 
the  sudden  increase  of  press- 
ure in  the  valve  destroys  the 
seal  in  the  tube  D,  by  forc- 
ing the  water  jnto  the  at- 
mosphere and  by  the  sealing  of  the  acetylene  inlet  tube,  thus 
allowing  the  explosive  mixture  to  escape  into  the  atmosphere. 

The  simple  type  of  valve  just  described  has  been  modified 
with  a  view  to  restoring  the  water  level  after  the  return  of  oxy- 
gen; dealing  with  explosions  in  the  valve;  sounding  an  alarm  in 
case  of  insufficient  water;  sealing  the  acetylene  inlet  tube  in 
case  of  insufficient  water.  Such  modifications  are  valuable 
where  important  equipment  and  numerous  welders  are  engaged. 
The  charging  of  the  valve  and  its  supervision  should  be  the  most 
important  duty  of  the  welder.  Its  position  should  be  such  that 


Machinery 


Fig.  11.  Hydraulic  Safety  Valve 


WELDING   EQUIPMENT  21 

all  valves  are  within  easy  reach,  and  it  should  be  possible  to  ex- 
amine the  interior  periodically  and  to  change  the  water  regularly. 

An  ordinary  water  bottle,  such  as  is  sometimes  used,  is  quite 
unsatisfactory,  and,  in  fact,  dangerous.  The  reason  for  using 
a  back-pressure  valve  is  one  of  such  importance  that  only  one 
correctly  proportioned  should  be  employed. 

Adjusting  the  Welding  Torch.  —  Before  lighting  the  torch, 
the  regulator  on  the  acetylene  line  should  be  set  to  give  the  re- 
quired pressure.  The  acetylene  is  then  lighted  and  turned  on 
full.  The  oxygen  is  then  turned  on,  and  the  pressure  varied  by 
means  of  the  regulator,  until  the  two  cones  which  appear  in  the 
flame  at  first  are  merged  into  one  smaller  cone.  After  this  cone 
is  formed,  no  more  oxygen  should  be  added.  It  is  also  well  to 
occasionally  test  the  cone  by  decreasing  the  oxygen  pressure 
slightly,  which  will  immediately  cause  an  extension  at  the  point 
of  the  cone.  When  the  cone  is  properly  formed,  it  will  be  neutral, 
so  that  it  will  neither  oxidize  (burn)  nor  carburize  the  metal. 
An  excess  of  oxygen  will  cause  burning  and  oxidation,  whereas 
an  excess  of  acetylene  will  carburize  the  metal.  The  tip  of  the 
cone  should  just  touch  the  metal  being  welded,  but  not  the  point 
of  the  torch,  as  this  might  cause  a  "  flash  back."  An  excessive 
discharge  of  sparks  indicates  that  too  much  oxygen  is  being 
used  and  that  the  metal  is  being  burned  or  oxidized,  although, 
when  welding  thick  metals,  there  will  be  a  considerable  volume 
of  sparks,  even  though  the  flame  is  neutral. 

Size  of  Torch  Tip.  —  The  proper  size  of  tip  to  use  for  welding 
depends  upon  the  thickness  of  the  work  and  the  rate  at  which  the 
heat  is  dissipated.  Sometimes  the  rate  of  conduction  and  radi- 
ation is  affected  by  the  location  of  the  parts  to  be  welded.  In 
general,  heavy  parts  will  conduct  the  heat  more  rapidly  from 
the  working  point,  and  to  offset  this  loss  of  heat  a  larger  tip  is 
used.  In  any  case,  the  tip  should  be  as  small  as  is  compatible 
with  good  work,  to  economize  in  the  use  of  gases.  If  the  flame 
is  too  small  for  the  thickness  of  metal  being  welded,  the  heat  will 
be  radiated  almost  as  fast  as  produced;  hence,  the  flame  will 
have  to  be  held  so  long  at  one  point  to  affect  a  weld  that  the  metal 
may  be  burned.  On  the  other  hand,  if  the  flame  is  too  large 


22  WELDING  EQUIPMENT 

the  radiation  may  be  insufficient  to  prevent  burning  the  molten 
metal.  The  tip  should  give  a  flame  that  will  reduce  the  metal 
to  a  plastic,  molten  condition  (not  too  fluid),  covering  a  width 
approximately  equal  to  the  thickness  of  the  metal  being  welded. 

Temperatures.  —  The  temperature  of  the  oxy-hydrogen  flame 
is  approximately  4000  degrees  F.,  and  the  temperature  of  the  oxy- 
acetylene  flame  is  about  6300  degrees  F.  With  the  oxy-acetylene 
flame,  the  number  of  British  thermal  units  per  cubic  foot  of  gas 
is  about  five  times  as  great  as  that  obtained  with  the  oxy-hydro- 
gen flame. 

Care  of  Apparatus.  —  Torches  and  other  apparatus  must  be 
given  proper  care.  If  anything  is  found  wrong,  such  as  leaks 
in  connections,  these  should  be  repaired  at  once,  and,  if  the  tips 
are  defective  and  cannot  be  repaired,  new  tips  should  be  provided. 
In  heavy  welding,  the  torch  tips,  if  made  of  brass,  are  liable  to 
be  overheated  unless  means  are  provided  for  cooling  the  tip. 
This  is  done  by  keeping  a  pail  of  water  near  by,  in  which  the  end 
of  the  tip  is  dipped  when  necessary.  The  whole  head  of  the 
torch  should  not  be  dipped,  as  this  is  liable  to  distort  the  end 
of  the  tip  at  the  seat  and  cause  a  leak.  The  best  method  is  to 
gradually  dip  the  end  of  the  tip  into  the  water,  thus  cooling  it 
slowly.  After  the  entire  tip  is  cooled,  the  head  may  also  be 
cooled  off,  but  not  rapidly. 

Oxy-acetylene  Apparatus.  —  There  are  three  general  types  of 
oxy-acetylene  apparatus  in  use  at  the  present  time,  namely: 

1.  Portable  apparatus. 

2.  Apparatus  consisting  of  an  acetylene  generator,  a  mani- 
fold for  attaching  oxygen  tanks,  or  a  storage  tank  for  oxygen, 
and  a'  system  of  piping  extended  throughout  the  shop. 

3.  Apparatus  using  both  oxygen  and  acetylene  generators, 
with  a  system  of  piping. 

The  field  of  the  portable  outfit  is  for  all  sorts  of  outside  work. 
It  may  also  be  used  in  shop  work,  but  is  rather  clumsy,  due 
to  the  weight  of  the  tanks  used  to  contain  acetylene;  although 
in  small  shops,  on  account  of  its  low  cost,  and  sometimes  because 
of  its  infrequent  use,  it  is  the  proper  type  to  use.  For  all-around 
effectiveness,  the  second  type  of  apparatus  is  superior  for  gen- 


WELDING   EQUIPMENT  23 

eral  shop  practice.  Practically  its  only  drawback  is  the  first 
cost  of  the  generator,  plant,  and  piping  system.  Once  installed, 
it  is  extremely  flexible  in  operation.  No  help  is  required  to  move 
tanks  around,  and  the  cost  of  the  gas  is  very  much  less,  being 
only  about  one-third  that  of  compressed  acetylene.  The  third 
type  of  apparatus  is  practically  the  same  as  the  second  except  that 
the  oxygen  as  well  as  the  acetylene  is  generated  on  the  ground. 
The  principal  disadvantage  of  the  system  is  its  very  high  cost, 
no  matter  what  process  is  used.  Also,  in  some  cases,  the  residue 
from  the  generator  is  very  disagreeable  to  handle. 

Methods  for  Producing  Oxygen.  —  Oxygen  is  a  gas  which 
constitutes  about  20  per  cent  of  the  air  in  the  atmosphere,  the 
other  80  per  cent  being  nitrogen,  a  gas  which  does  not  support 
combustion.  Oxygen,  however,  is  the  active  agent  in  maintaining 
life  and  combustion;  its  properties  have  been  known  since 
the  end  of  the  eighteenth  century.  Oxygen  can  be  produced 
in  several  ways  at  such  a  price  as  to  make  it  commercially  useful. 

Liquid-air  Process.  —  At  the  present  time  the  largest  pro- 
portion of  oxygen  is  made  by  the  liquid-air  process  invented  by 
Dr.  Linde  in  1897.  Almost  every  one  remembers  the  demon- 
strations a  few  years  ago  of  liquid  air,  and  of  the  many  curious 
and  interesting  things  that  were  done  by  its  use.  Most  of  these 
things,  however,  were  mere  laboratory  experiments,  and  its  most 
important  application,  that  of  producing  oxygen  for  commer- 
cial use,  was  not  thought  of  at  that  time.  The  possibility  of 
producing  oxygen  in  this  way  has  been  one  of  the  chief  factors 
in  promoting  the  use  of  oxy-acetylene  welding,  as  it  has  re- 
duced the  cost  of  the  oxygen.  The  process  simply  consists 
in  liquefying  air  and  allowing  it  to  again  vaporize.  The  boil- 
ing points  of  oxygen  and  nitrogen  are  considerably  different; 
hence,  the  gas  desired  may  be  collected  and  the  other  allowed  to 
evaporate.  The  oxygen,  after  purification,  is  compressed  into 
cylinders  or  tanks,  and  can  then  be  shipped  wherever  it  is  desired 
for  use.  The  principal  impurity  in  oxygen  thus  made  is  nitro- 
gen, a  percentage  of  which  is  likely  to  be  present,  and  which, 
even  when  small,  has  an  adverse  effect  on  a  weld,  and  is  particu- 
larly objectionable  when  using  a  cutting  torch. 


24  WELDING   EQUIPMENT 

Electrolytic  Process.  —  The  next  most  important  process 
for  producing  oxygen  is  the  electrolytic.  The  decomposition  of 
water  by  ejectric  current  into  its  two  elements  oxygen  and 
hydrogen,  has  been  practiced  for  many  years;  but  it  was  not  until 
the  cost  of  electric  current  was  reduced  to  a  low  point  that  it 
was  possible  to  use  this  process  commercially.  It  was  also  found 
by  experiment  and  test  that  the  production  of  an  efficient  and 
safe  electrolytic  cell  was  not  an  easy  matter.  It  is,  however, 
at  the  present  time,  a  thoroughly  practical  process,  and  one  which 
is  gaining  ground  daily.  It  is  exceedingly  flexible,  and  while  the 
cost  of  cells  is  prohibitive  for  a  small  plant,  yet,  where  consid- 
erable oxygen  is  used  with  regularity  and  the  expense  can  be 
afforded,  it  is  much  used,  as  it  produces  the  purest  commercial 
oxygen.  The  only  impurity  in  it  of  any  importance  is  a  small 
percentage  of  hydrogen,  which  does  not  injure  the  weld,  nor  is 
it  of  disadvantage  in  cutting,  as  it  burns,  producing  heat. 

Chlorate-of-potash  Process.  —  There  are  a  number  of  other 
processes  for  producing  oxygen,  the  only  important  one  being 
by  heating  chlorate  of  potash  in  a  retort,  passing  the  gas  through 
a  washing  apparatus,  and  collecting  it  in  a  gasometer.  It  can 
then  be  compressed  to  the  required  pressure  and  used  as  needed. 
Oxygen  should  never  be  generated  from  chlorate  of  potash 
under  a  pressure  of  more  than  a  few  ounces,  on  account  of  the 
danger  of  explosion.  Oxygen,  particularly  when  moist,  as  after 
passing  through  a  washer,  attacks  the  piping,  etc.,  resulting  in 
a  weakening  of  the  pipes,  which  cannot  be  generally  detected 
in  time  to  prevent  serious  results.  Oxygen  is  also  liable  to 
cause  an  explosion  when  it  is  heated  and  comes  into  contact  with 
any  carbonaceous  material,  such  as  splinters  of  wood,  in  the 
retort.  Serious  accidents  have  occurred  from  this  cause.  The 
method,  however,  is  perfectly  safe  if  care  is  taken  and  the  appa- 
ratus is  procured  from  reliable  manufacturers.  The  generation 
of  oxygen  from  chlorate  of  potash  under  pressure  is  considered 
much  more  hazardous. 

The  gas  produced  by  the  chlorate-of -potash  process  is  quite 
expensive,  and  contains  a  certain  -amount  of  chlorine  which  is 
detrimental  to  the  strength  of  the  welds  and,  therefore,  unsat- 


WELDING  EQUIPMENT  25 

isfactory.  This  chlorine,  however,  can  be  removed  entirely  if 
proper  apparatus  is  used,  and,  under  certain  circumstances,  as 
where  the  cost  of  shipping  tanks  back  and  forth  is  very  high, 
the  use  of  chlorate  of  potash  for  generating  oxygen  may  be 
advisable.  At  the  present  time  the  European  war  has  greatly 
increased  the  cost  of  chlorate  of  potash,  and  this  should  be  con- 
sidered in  making  estimates. 

Commercial  Oxygen.  —  As  commercially  used  in  the  oxy- 
acetylene  welding  industry,  oxygen  may  be  made  or  bought. 
The  latter  is  the  cheaper  method,  if  the  location  is  near  a  large 
plant  making  oxygen  as  a  commercial  product,  as  it  saves  the 
installing  of  a  somewhat  expensive  apparatus.  If  it  is  necessary 
to  make  oxygen,  either  on  account  of  cost  or  irregularity  in  deliv- 
ery, the  best  process  on  a  small  scale  is  the  heating  of  chlorate  of 
potash  in  closed  retorts,  the  resulting  gas  being  passed  through 
washers  and  collected  in  a  gasometer,  as  described,  from  which 
it  is  pumped  into  tanks  by  a  small  compressor,  generally  belt- 
driven.  The  usual  maximum  pressure  in  the  tanks  is  about  300 
pounds,  and  they  generally  have  a  capacity  of  100  cubic  feet  of 
oxygen  measured  at  atmospheric  pressure.  These  tanks  are 
convenient  for  shop  use,  but  for  outside  work  they  are  somewhat 
heavy  and  bulky,  and  can  be  replaced  with  advantage  by  smaller 
tanks  of  the  same  capacity,  but  having  a  pressure  of  about  1800 
pounds  per  square  inch.  These  tanks  are  not  sold,  but  are 
furnished,  filled  with  oxygen,  by  the  oxygen  companies  on  rea- 
sonable terms,  and,  when  empty,  may  be  returned  for  refilling. 
Oxygen  can  be  obtained  in  this  way  much  more  cheaply  and 
conveniently  under  ordinary  conditions  than  by  making  it.  It 
should  be  noted  that  all  tanks  shipped  must  comply  in  all  respects 
with  the  requirements  of  the  Federal  Bureau  of  Explosives. 

Potassium-chlorate  Method  of  Oxygen  Generation.  —  A  dia- 
grammatic view  of  the  apparatus  used  for  making  oxygen  by 
the  potassium-chlorate  method  is  shown  in  Fig.  6.  The  potas- 
sium chlorate  is  sealed  in  a  retort  A  and  heated  by  gas  burners 
B.  The  heating  causes  the  potassium  chlorate  to  give  off 
oxygen,  but  this  reaction  would  proceed  too  rapidly  if  the  charge 
placed  in  the  retort  consisted  of  pure  potassium  chlorate.  It 


26  WELDING  EQUIPMENT 

has  been  found,  however,  that,  by  mixing  13  pounds  of  manganese 
dioxide  with  100  pounds  of  potassium  chlorate,  the  chemical 
reaction  will  proceed  more  slowly.  The  manganese  dioxide 
plays  no  part  in  the  chemical  reaction,  but  is  merely  used  as  a 
retarding  agent.  Ten  pounds  of  the  mixture  is  put  in  the  retort 
at  a  time.  The  gas  from  the  retort  is  delivered  through  a  series 
of  three  washers  C,  which  serve  to  remove  impurities,  after  which 
it  passes  on  and  is  collected  in  the  gasometer  D.  From  the 
gasometer,  the  oxygen  is  piped  to  the  compressor  E,  which  com- 
presses it  into  cylinders  at  the  required  pressure  ready  for  use. 
The  purity  of  the  oxygen  obtained  by  this  method  is  slightly 
over  97  per  cent. 

Manufacture  of  Oxygen  by  the  Liquid-air  Process.  —  In  the 
manufacture  of  oxygen  by  the  liquid-air  process,  the  oxygen  is 
obtained  by  making  a  separation  of  the  oxygen  and  nitrogen, 
which  are  the  chief  constituents  of  air.  This  is  done  by  first 
bringing  the  air  to  the  liquid  condition  by  the  combined  action 
of  high  pressure  and  low  temperature,  and  then  separating  the 
oxygen  from  the  nitrogen  by  taking  advantage  of  the  difference 
in  the  boiling  points  of  these  two  constituents  of  the  air  when 
in  the  liquid  condition.  This  method  allows  oxygen  to  be  ob- 
tained at  a  relatively  low  cost,  but  the  plant  required  is  only 
suitable  for  working  on  a  large  scale.  Consequently,  the  method 
is  suitable  for  the  use  of  manufacturers  of  oxygen  rather  than  for 
the  users  of  welding  and  cutting  torches  who  desire  to  make 
only  enough  oxygen  for  their  own  use.  It  is  for  this  reason  that 
many  users  of  welding  and  cutting  torches  have  found  it  more 
advantageous  to  buy  their  oxygen  in  cylinders  ready  for  use  than 
to  make  their  own  supply  in  a  potassium  chlorate  or  an  electro- 
lytic plant. 

To  meet  the  demand  from  this  class  of  consumers,  generating 
plants  have  been  established  in  the  most  important  industrial 
centers  throughout  the  United  States.  These  plants  supply 
oxygen  to  the  consumer,  which  is  contained  in  pressure  cylinders 
ready  for  use;  and,  as  a  result  of  these  numerous  plants,  many 
consumers  get  the  advantage  of  buying  their  oxygen  without 
having  to  pay  freight  on  the  filled  cylinders  or  on  the  empty  ones 


WELDING  EQUIPMENT  27 

which  must  be  returned  to  the  generating  plants.  In  many  cities 
where  there  is  not  enough  manufacturing  to  warrant  the  mainte- 
nance of  generating  plants,  warehouses  have  been  established 
in  which  a  supply  of  filled  oxygen  cylinders  is  carried  so  that 
orders  can  be  promptly  filled;  but  in  these  cases  the  price  is 
necessarily  higher,  as  freight  charges  must  be  included. 

It  has  already  been  stated  that  the  method  by  which  oxygen 
is  obtained  from  the  mixture  of  nitrogen  and  oxygen  in  the  air 
consists  of  first  bringing  the  air  to  the  liquid  condition  by  the 
combined  application  of  high  pressure  and  low  temperature,  and 
then  separating  the  oxygen  and  nitrogen  by  allowing  the  nitro- 
gen to  boil  off  from  the  mixed  liquid.  Fig.  1 2  shows  a  diagram- 
matic view  of  the  plant  employed  for  this  purpose.  This  diagram 
gives  a  comprehensive  idea  of  the  principle  involved  and  the 
general  character  of  the  equipment  which  is  used.  The  diagram 
is  presented  simply  as  an  adjunct  to  the  following  description, 
and  many  details  have  been  omitted.  It  is  well  known  that 
atmospheric  air  contains  appreciable  quantities  of  carbon  dioxide, 
and  the  first  step  in  the  manufacture  of  oxygen  by  the  liquid- 
air  method  is  to  remove  the  carbon  dioxide.  This  is  done  by 
drawing  the  air  through  a  pit  containing  lime,  which  absorbs 
the  carbon  dioxide  by  a  chemical  reaction  resulting  in  the  forma- 
tion of  a  compound  known  as  calcium  carbide.  After  leaving 
the  lime  pit,  the  air  goes  to  a  five-stage  compressor,  in  which  the 
pressure  is  raised  to  3000  pounds  per  square  inch,  and  means 
are  provided  for  cooling  the  air  between  each  stage  of  compres- 
sion, so  that  it  leaves  the  compressor  at  about  room  temperature. 
After  leaving  the  compressor,  the  air  is  delivered  through  pipe 
A  to  the  "  fore-cooler,"  in  which  the  first  reduction  of  temperature 
is  effected.  This  fore-cooler  is  equipped  with  three  sets  of 
coils.  The  first  coil  contains  carbon  dioxide  supplied  from  an 
external  refrigerating  system,  and  the  other  two  coils  contain 
the  oxygen  and  nitrogen  gases  which  have  already  been  separated 
from  the  liquid  air  and  are  at  very  low  temperatures. 

As  a  result  of  its  passage  through  the  fore-cooler,  the  tem- 
perature of  the  air  has  been  reduced  to  about  o  degrees  C.  After 
passing  through  the  fore-cooler,  the  air  enters  pipe  B,  which 


WELDING   EQUIPMENT  $g 

carries  it  to  a  third  unit  of  the  plant,  known  as  an  "  interchanges" 
This  pipe  B  leads  to  a  coil  C,  which  is  submerged  in  the  liquid 
air  in  the  interchanger,  and  the  purpose  of  passing  the  air  through 
this  coil  will  be  subsequently  explained.  After  leaving  the  coil 
C,  the  air,  which  it  will  be  remembered  is  at  a  pressure  of  3000 
pounds  per  square  inch,  is  allowed  to  pass  through  an  expansion 
valve  D,  where  the  pressure  is  suddenly  released.  This  results 
in  a  rapid  expansion  of  the  air,  that,  in  turn,  causes  a  further 
reduction  of  temperature,  with  the  result  that  the  air  is  brought 
to  the  liquid  condition  by  this  application  of  the  Thomson- 
Joule  principle.  The  liquid  air  passes  through  the  vertical  pipe 
to  the  top  of  the  interchanger,  where  it  is  discharged  through 
the  atomizer  E,  which  is  located  at  the  top  of  a  tower  filled  with 
perforated  baffle  plates  F.  The  liquid  air  passes  down  over 
these  baffle  plates  and  finally  reaches  the  container  in  which 
the  coil  C  is  submerged. 

We  are  now  in  a  position  to  go  back  to  the  reference  which  was 
made  to  the  purpose  of  the  coil  C.  It  will  be  recalled  that  the 
air  left  the  fore-cooler  at  a  temperature  of  approximately  o 
degrees,  and  although  this  is  a  relatively  low  temperature,  it  is 
quite  high  when  compared  with  the  boiling  points  of  liquid 
nitrogen  and  oxygen,  which  are  194  and  184  degrees  C.  below 
zero,  respectively.  The  result  is  that  the  passage  of  the  air 
through  coil  C  causes  the  liquid  in  the  container  to  boil  in  the 
same  way  that  a  coil  containing  high-pressure  steam  would  cause 
water  to  boil.  But  as  the  boiling  point  of  nitrogen  is  10  de- 
grees higher  than  that  of  oxygen,  the  nitrogen  must  be  removed 
from  the  liquid  before  the  oxygen  will  start  to  boil.  The  result 
is  that  the  nitrogen  passes  up  through  the  baffle  plates  F  in 
the  tower,  and  in  so  doing  heats  the  liquid  air  sufficiently  to 
remove  a  large  part  of  the  nitrogen  before  the  liquid  actually 
reaches  the  container.  The  boiling  of  the  nitrogen  sets  up  a 
pressure  in  the  interchanger  which  is  sufficient  to  force  the  liquid 
oxygen  up  through  the  pipe  G  into  the  inner  tube  of  the  double 
coil  H  which  surrounds  the  tower  in  which  the  baffle  plates  F 
are  located;  and  the  nitrogen  which  has  been  removed  from  the 
mixture  passes  down  through  the  outer  tube  of  the  coil  H  which 


30  WELDING  EQUIPMENT 

surrounds  the  tube  carrying  the  oxygen.  The  result  is  that  the 
oxygen  gradually  rises  through  the  inner  tube  of  the  coil,  and 
while  doing  so  changes  from  the  liquid  to  the  gaseous  condition. 
In  order  to  keep  the  temperature  of  the  interchanger  down, 
the  coils  and  other  portions  of  the  apparatus  are  carefully  insu- 
lated by  packing  the  space  in  the  outer  case  with  lamb's  wool 
which  effectually  prevents  the  absorption  of  heat  from  the 
outside. 

After  passing  through  the  coil  H  in  the  interchanger,  the 
pipes  containing  the  oxygen  and  nitrogen  —  which  are  still  at 
a  very  low  temperature  —  are  carried  over  to  the  fore-cooler, 
where  they  enter  two  coils.  It  will  be  recalled  that,  in  the 
preceding  description  of  the  fore-cooler,  mention  was  made  of 
these  coils  through  which  the  low-temperature  oxygen  and 
nitrogen  were  passed.  The  purpose  is  to  utilize  the  low  tempera- 
ture of  these  gases  to  assist  the  carbon-dioxide  coil  in  reducing 
the  temperature  of  the  air  as  it  passes  through  the  fore-cooler 
on  its  way  to  the  interchanger.  After  passing  through  the  coil 
in  the  fore-cooler,  the  oxygen  and  nitrogen  pass  out  through 
pipes,  and  the  oxygen  is  ready  to  be  collected  in  compression 
cylinders.  At  the  present  time  the  only  use  for  the  pure  nitro- 
gen which  is  made  by  this  method  is  in  incandescent  electric 
light  bulbs.  Nitrogen  is  very  suitable  for  this  purpose,  because 
it  is  chemically  inert,  and  so  does  not  have  any  effect  upon  the 
incandescent  filament.  Research  work  is  also  done  with  the 
view  of  developing  a  method  of  " fixing"  the  nitrogen;  i.e.  of 
developing  a  method  of  chemically  combining  the  nitrogen 
with  some  other  element  or  elements  so  that  it  may  be  used  as 
a  fertilizer,  and  in  various  chemical  industries.  The  Linde 
Air  Products  Co.  is  prepared  to  guarantee  a  purity  of  98.5  per 
cent  for  its  oxygen,  and,  as  a  matter  of  fact,  the  purity  is  in  the 
neighborhood  of  99  per  cent.  The  i  per  cent  of  impurity  is 
nitrogen,  which  is  chemically  inert,  so  that  it  has  little  detrimental 
effect  upon  the  steel  or  other  metal  which  is  being  welded. 

The  Electrolytic  Method  of  Generating  Oxygen.  —  For  those 
shops  which  use  oxygen  in  sufficient  quantities  to  warrant  the 
installation  of  a  plant  for  generating  the  gas  by  the  electrolysis 


WELDING   EQUIPMENT 


of  water,  there  is  probably  no  more  satisfactory  method.  It 
is  well  known  that  water  is  composed  of  two  parts  of  hydrogen 
chemically  united  to  one  part  of  oxygen,  and  that  when  an 
electric  current  is  passed  through  water  —  with  the  necessary 
amount  of  sodium  hy- 
droxide, potassium  hy- 
droxide, or  some  other 
chemical  dissolved  in  it 
to  make  the  solution  a 
conductor  of  electricity 
—  the  chemical  bond  be- 
tween the  hydrogen  and 
oxygen  will  be  broken 
down.  The  result  is  that 
hydrogen  gas  is  given 
off  at  the  cathode  or 
negative  pole,  and  that 
oxygen  is  liberated  at  the 
anode  or  positive  pole 
of  the  electrolytic  cell. 

In  the  manufacture  of 
oxygen  by  this  method, 
the  electrolyzer  in  which 
the  dissociation  of  the 
hydrogen  and  oxygen 
takes  place  is  so  arranged 
that  the  two  gases  are 
kept  separate  from  each 
other  and  carried  off 
through  individual  pipes. 
Fig.  13  shows  the  ar- 


Machincry 


Fig.  13.   One  of  the  Cells  used  in  Electrolytic 
Ozygen  Manufacture 


rangement  of  the  type 
of  electrolytic  cell  made 
by  the  Davis-Bournonville  Co.  The  reservoir  in  which  the  po- 
tassium-hydroxide solution  is  contained  is  divided  by  a  metal 
plate  A;  and  an  anode  B,  on  which  the  oxygen  is  formed,  is 
suspended  in  the  solution  on  each  side  of  the  partition.  The 


32 


WELDING   EQUIPMENT 


cell  itself  is  made  of  metal,  and  the  container  and  metal  parti- 
tion form  the  cathode  or  negative  pole  from  which  hydrogen  is 
evolved.  To  provide  for  keeping  the  oxygen  and  hydrogen  sepa- 
rate, an  asbestos  curtain  C  surrounds  each  of  the  anodes  B;  this 
curtain  extends  almost  to  the  top  of  the  cell  and  keeps  the  oxy- 
gen separate  from  the  hydrogen.  The  oxygen  gas  is  carried  off 
through  the  two  pipes  D  which  are  connected  with  the  off-take 


FIFTEEN  ELECTROLYTIC  CELLS -SPACE  ANp  ARRANGEMENT  ALLOW 
FIFTEEN  ADDITIONAL  CELLS 


VceMacry 


Fig.  14.   Plan  of  Electrolytic  Oxygen  Plant 

pipe  E,  that  carries  the  oxygen  from  all  of  the  cells  to  the  gas- 
holder in  which  it  is  collected.  Similarly,  the  hydrogen  is  carried 
off  from  the  cell  through  pipe  F,  which  is  connected  with  pipe  G 
that  carries  the  hydrogen  from  all  of  the  cells. 

When  the  electric  current  is  passed  through  the  cell,  the 
entire  volume  of  water  is  placed  in  a  state  of  charge,  which 
results  in  the  liberation  of  oxygen  at  the  anode  and  hydrogen 
at  the  cathode.  There  is  no  tendency  for  these  gases  to  be 
liberated  at  any  point  except  at  their  respective  terminals  in 


WELDING  EQUIPMENT  33 

the  cell,  and  so  the  asbestos  separator  C  will  keep  the  two  gases 
from  mixing.  It  is  important,  however,  for  the  pressure  of  the 
oxygen  and  hydrogen  to  be  kept  the  same,  in  order  to  avoid 
the  tendency  for  the  gas  at  higher  pressure  to  be  forced  through 
the  asbestos  curtain.  This  equalization  of  the  pressure  is  pro- 
vided for  by  having  the  two  pipes  E  and  G  pass  the  gas  which 
they  carry  through  two  water  seals.  These  are  arranged  so  that 
the  pressure  head  of  water  is  the  same  in  each  seal,  and,  as  a 
result,  the  back  pressure  exerted  on  the  oxygen  and  hydrogen 
leaving  the  cells  is  maintained  exactly  the  same.  Some  factories 
make  a  practice  of  collecting  the  hydrogen  gas  which  is  generated, 
for  use  in  oxy-hydric  cutting  torches;  and,  in  certain  cases,  the 
hydrogen  has  been  employed  for  filling  the  bulbs  of  incandescent 
electric  lights.  In  many  shops,  however,  it  is  not  found  worth 
while  to  attempt  to  utilize  the  hydrogen,  and  in  such  cases  this 
gas  is  allowed  to  pass  off  into  the  atmosphere. 

Complete  Plant  for  Electrolytic  Oxygen  Production.  —  Fig.  14 
shows  the  arrangement  of  a  complete  plant  for  the  generation 
of  oxygen  and  hydrogen  by  the  electrolytic  method,  in  which 
provision  is  made  for  collecting  both  the  oxygen  and  hydrogen. 
In  this  illustration  the  motor  generator  which  supplies  current 
to  the  electrolytic  cells  is  shown  at  A.  The  cells  are  shown  at 
B;  the  gas-holders  for  the  oxygen  and  hydrogen,  at  C  and  D, 
respectively;  the  compressors  for  compressing  the  oxygen 
and  hydrogen,  at  E  and  F;  and  the  pressure  tanks  to  which  the 
compressors  deliver  the  oxygen  and  hydrogen,  at  G  and  H. 
It  will  also  be  noted  that  provision  is  made  for  connecting  port- 
able cylinders  /  and  /  direct  to  the  compressors  so  that  these 
cylinders  may  be  filled  with  oxygen  and  hydrogen. 

In  presenting  a  description  of  the  operation  of  the  plant,  it 
will  simplify  matters  to  refer  only  to  the  equipment  used  for 
the  generation  and  compression  of  the  oxygen.  The  equip- 
ment shown  for  handling  the  hydrogen  works  on  exactly  the 
same  principle,  so  that  one  description  will  apply  in  both  cases. 
Upon  leaving  the  electrolytic  cells  B,  the  oxygen  is  passed  along 
to  the  gas-holder  C,  which  is  of  the  standard  type,  in  which  an 
inverted  bell  is  suspended  over  water  by  means  of  a  counter- 


34  WELDING  EQUIPMENT 

weight.  As  the  oxygen  enters  the  gas-holder,  the  bell  rises, 
and  when  it  has  reached  a  predetermined  limit  —  or  when  the 
gas-holder  is  filled  to  its  capacity  —  an  automatic  switch  is  thrown 
which  starts  the  electric  motor  that  drives  the  oxygen  compressor 
E.  This  results  in  pumping  oxygen  out  of  the  gas-holder  and 
compressing  it  in  the  oxygen  pressure  tanks  G.  These  tanks 
are  usually  arranged  for  a  maximum  pressure  of  300  pounds 
per  square  inch,  and,  when  this  has  been  obtained,  a  pressure 
regulator  of  the  Bourdon  spring  type,  which  is  located  on  the 
switchboard  K,  throws  a  relay  that,  in  turn,  trips  the  compressor 
motor  switch  and  stops  the  compressor. 

While  the  compressor  is  in  action,  it  will  be  evident  that 
oxygen  is  being  withdrawn  from  the  gas-holder  C,  with  the 
result  that  the  bell  descends;  and  when  the  bell  has  reached 
the  lower  limit  of  its  travel  —  so  that  practically  all  of  the 
oxygen  has  been  pumped  out  of  the  holder  —  an  independent 
electric  switch  will  be  thrown  to  stop  the  compressor  motor. 
When  the  compressor  is  stopped  in  this  way,  the  motor  generator 
A  continues  to  run  so  that  the  supply  of  oxygen  from  the  elec- 
trolytic cells  B  is  continued  until  the  gas-holder  C  is  filled  to 
its  capacity.  When  this  result  is  obtained,  the  normal  sequence 
of  events  would  be  for  the  switch  which  governs  the  compressor 
motor  to  be  thrown  over,  in  order  to  start  the  compressor.  It 
may  happen,  however,  that  the  pressure  in  the  oxygen  tanks 
G  is  at  the  maximum  of  300  pounds  per  square  inch;  when  such 
is  the  case,  means  are  provided  to  make  it  impossible  for  the 
switch  to  be  thrown  to  start  the  compressor  motor.  Under  such 
conditions,  an  automatic  switch  is  thrown,  which  stops  the  motor 
generator  and  cuts  off  the  generation  of  oxygen  in  the  electro- 
lytic cells.  As  soon  as  the  oxygen  in  the  pressure  tanks  has  been 
partially  consumed,  thus  lowering  the  pressure,  the  compressor 
motor  automatically  starts  to  deliver  more  oxygen  to  the 
pressure  tanks,  with  the  result  that  the  gas-holder  starts  to 
descend.  This,  in  turn,  closes  the  switch  controlling  the  motor- 
generator  set,  which  restarts  the  motor-generator  and  causes 
the  electrolytic  cells  to  begin  to  generate  more  oxygen.  The 
500- ampere  cell  requires  i|  gallon  of  water  to  be  added  each 


WELDING  EQUIPMENT  35 

twenty-four  hours,  and  the  looo-ampere  cell  requires  2\  gallons 
of  water  per  twenty-four  hours;  otherwise  the  only  attention 
necessary  is  the  maintenance  of  the  different  units  of  the  plant 
in  running  order,  and  this  takes  very  little  time.  The  purity 
of  the  oxygen  generated  by  this  process  is  in  excess  of  99  per 
cent. 

Influence  of  Impurities  in  Oxygen.  —  It  is  of  considerable 
importance  that  the  oxygen  should  be  as  pure  as  possible.  The 
impurities  which  decrease  efficiency  are  nitrogen  or  hydrogen. 
When  oxygen  is  prepared  by  the  liquid-air  process,  a  certain 
percentage  of  nitrogen  is  always  certain  to  be  present;  nitrogen 
tends  to  cool  the  heating  flame.  In  the  manufacture  of  oxygen 
by  the  electrolytic  process,  the  only  impurity  is  hydrogen.  The 
effects  of  the  presence  of  nitrogen  are  especially  noticeable  when 
cutting  operations  are  done  by  the  oxy-acetylene  or  oxy-hydrogen 
torch.  Experiments  have  been  carried  out  in  order  to  determine 
just  how  serious  the  effect  of  nitrogen  in  oxygen  is.  These 
experiments  show  that  the  purity  of  oxygen  plays  a  most  impor- 
tant part  in  the  efficiency  with  which  the  cutting  operations 
may  be  accomplished.  With  oxygen  about  85  per  cent  pure, 
it  requires  three  times  as  long  to  cut  a  plate  an  inch  thick  as  when 
the  oxygen  is  99  per  cent  pure.  Even  the  one-half  of  one  per 
cent  drop  from  99  per  cent  oxygen  to  98.5  per  cent  quality  means 
a  decrease  in  efficiency  of  16  per  cent.  Hence,  even  if  the  better 
grade  of  oxygen  costs  somewhat  more,  it  is  apparent  that  it  must 
cost  a  great  deal  more  in  order  that  it  should  be  more  expensive 
to  use  than  the  cheaper  grades.  It  is,  therefore,  essential  to 
obtain  oxygen  as  free  as  possible  from  nitrogen;  but  the  adverse 
effects  of  hydrogen  on  cutting  work  are  practically  negligible. 

Acetylene.  —  Acetylene  has  been  known  for  a  great  number 
of  years,  having  been  discovered  in  1836,  but  until  1892  its 
production  was  merely  a  laboratory  experiment.  In  that  year 
calcium  carbide  was  accidentally  manufactured  in  an  electric 
furnace  at  the  works  of  the  Willson  Aluminum  Co.,  in  North 
Carolina.  It  was  considered  of  no  value  and  was  thrown  into 
the  river.  It  was  then  accidentally  discovered  that  the  gas 
arising  from  it  when  thrown  into  water  would  ignite,  and  a 


36  WELDING  EQUIPMENT 

further  investigation  proved  that  this  was  acetylene.  Its  com- 
mercial exploitation  began  shortly  afterward  in  its  use  for 
isolated  lighting  plants,  as  in  a  suitable  burner  it  produces  an 
intensely  white  and  very  pleasing  flame;  and,  as  the  generation 
is  comparatively  easy  and  safe,  it  has  attained  a  wide  popularity. 
Acetylene  is  composed  entirely  of  carbon  and  hydrogen,  both 
of  which  elements,  when  combined  with  oxygen,  burn,  producing 
heat.  Acetylene  has  the  property,  if  completely  burned,  of 


Fig.  15.   International  Oxygen  Co.'s  Apparatus  for  Making  Oxygen 

producing  the  maximum  temperature  possible  in  a  gas  flame. 
This  was  appreciated  by  a  number  of  experimenters,  but  they 
found  great  danger  from  its  explosive  properties.  For  instance, 
if  mixed  with  air  and  compressed  to  about  30  pounds'  gage 
pressure,  it  explodes.  Even  if  not  mixed  with  air  it  cannot 
be  compressed  above  this  pressure  and  subjected  to  heat,  shock, 
or  other  disturbances  without  being  decomposed  into  its  elements; 
and  then  a  violent  explosion  results.  This  is  one  reason  why 
acetylene  generators  must  be  properly  designed  and  taken  care 


WELDING  EQUIPMENT  37 

of;  also,  to  prevent  overheating,  a  large  excess  of  water  should 
be  used,  as  one  pound  of  carbide  will  raise  the  temperature  of 
one  gallon  of  water  90  degrees  F. 

Acetone  for  Storing  Acetylene.  —  It  has  been  found,  however, 
that  certain  liquids  have  the  peculiar  property  of  absorbing 
many  volumes  of  acetylene.  The  most  satisfactory  liquid  for 
this  purpose  is  acetone,  and  this  is  used  in  all  compressed  acety- 
lene tanks  at  the  present  time.  It  is  also  found  advantageous 
and  safer  to  fill  these  cylinders  completely  full  of  asbestos  or 
other  porous  material,  so  that  there  will  be  no  chance  of  dead 
spaces  which  might  otherwise  become  filled  with  air  and  make 
the  cylinders  more  or  less  unsafe.  In  this  porous  material  is 
contained  the  acetone,  and  in  the  acetone  is  dissolved  the  acety- 
lene. It  is  perfectly  safe  to  store  compressed  acetylene  in  such 
tanks,  and  they  have  been  subjected  to  the  most  violent  shocks, 
such  as  firing  a  rifle  bullet  through  them,  dropping  large  weights 
on  them,  and  even  putting  them  into  hot  fires,  without  explosion; 
but  the  actual  process  of  compressing  the  acetylene  in  the  tanks 
is  still  accompanied  by  danger,  if  attempted  by  inexperienced 
men.  It  should  be  done  only  by  those  who  thoroughly  under- 
stand this  work,  and  the  nature  of  acetylene.  Hence  no  attempt 
should  be  made  to  transfer  acetylene  from  one  tank  to  another, 
as  has  been  sometimes  suggested.  Acetylene  may  also  be  pro- 
duced in  a  generator  suitable  for  the  purpose  by  bringing  in  con- 
tact water  and  calcium  carbide.  This  produces  gas  more  cheaply 
than  that  furnished  in  tanks,  and,  if  the  generator  is  of  the  proper 
design,  it  will  be  found  entirely  satisfactory  for  most  welding. 

Generating  Acetylene  Gas.  —  When  calcium  carbide  is 
brought  into  contact  with  water,  acetylene  is  given  off  and  slaked 
lime  left  as  a  residue.  There  are  three  kinds  of  generators,  the 
essential  differences  being  the  methods  of  uniting  the  carbide 
and  the  water.  These  methods  are: 

1.  Dropping  the  carbide  into  a  large  body  of  water. 

2.  Allowing  the  water  to  rise  slowly  against  the  carbide. 

3.  Dropping  the  water  on  the  carbide. 

The  first  is  by  far  the  safest  method;  it  keeps  the  pressure 
uniform,  gives  cooler  and  purer  gas,  and  is  in  every  way  to  be 


38  WELDING  .EQUIPMENT 

preferred.  In  any  case,  the  directions  furnished  by  the  makers 
of  the  generator  should  be  strictly  followed,  or  an  explosion 
may  result.  The  safety  valve  should  be  tested  daily  to  be  sure 
that  it  is  working  properly;  the  regulator  should  be  kept  in  con- 
dition so  that  the  working  pressure  will  be  kept  within  proper 
limits;  leaks  of  all  kinds  should  be  carefully  avoided;  and  the 
feeding  mechanism  should  be  stopped,  and  the  cut-out  valve  in 
the  supply  pipe  shut  off  every  night  or  when  the  generator  is  out 
of  service  for  any  length  of  time.  Keep  flames  or  lights  of  any 
kind  away.  An  excess  of  caution  is  advisable  in  handling 
acetylene,  and  the  matter  of  insurance  should  receive  special 
attention,  as  improper  location  or  installation  may  invalidate 
any  insurance  in  force.  If  the  generator  is  worked  too  hard 
it  will  become  hot,  and  in  this  condition  is  dangerous.  The 
maker  can  say  how  many  torches  of  a  given  size  should  be  con- 
nected and  working  at  one  time.  If  a  generator  becomes  hot 
for  any  reason,  stop  the  use  and  generation  of  gas  until  it  is 
cooled  down,  no  matter  how  long  it  takes. 

Precautions  in  the  Use  of  Acetylene  Generators.  —  A  gener- 
ator containing  carbide  should  never  be  moved  around;  it  is 
liable  to  be  upset,  and  the  water,  coming  suddenly  in  contact 
with  a  large  quantity  of  the  carbide,  will  raise  the  pressure  to 
the  explosive  point,  which  is  about  30  pounds  per  square  inch 
when  acetylene  has  any  air  mixed  with  it.  Fatal  accidents  have 
occurred  from  this.  Freezing  must  be  guarded  against,  but, 
if  thawing  out  is  necessary,  hot  water  applied  externally  is  the 
only  safe  method  to  use.  Where  flash-back  chambers  are  pro- 
vided, keep  them  in  proper  condition,  filling  them  with  water 
every  time  carbide  is  put  in.  If  any  part  of  the  generator  is 
not  understood  by  the  user,  consult  the  manufacturers;  they 
will  give  full  instructions  and  advice. 

The  end  of  the  discharge  pipe  for  the  residue  should  be  where 
it  can  be  seen,  so  that  if  there  is  a  loss  of  water,  due  to  a  leaky 
valve,  it  can  be  noticed.  If  water  is  gradually  lost,  it  may  in 
time  entirely  drain  out,  and  the  generator  will  run  hot.  It  will 
not  give  a  sufficient  or  uniform  supply  of  gas  and  will  be  in  a 
dangerous  condition.  Do  not  open  the  hand-hole,  or  any  open- 


WELDING   EQUIPMENT  39 

ing  in  the  body  of  the  generator,  under  such  conditions,  as  it 
is  liable  to  produce  an  explosion.  Let  the  generator  cool  down 
until  it  reaches  the  room  temperature.  The  proper  method 
of  handling  depends  upon  the  type  of  generator,  and  if  one  is  not 
sure  what  to  do,  he  should  consult  the  manufacturer.  Explo- 
sions Will  never  occur  if  the  generator  is  watched  and  handled 
in  the  proper  way. 

Types  of  Generators.  —  There  are  two  general  types  of  acety- 
lene generators  used  in  the  United  States,  which  are  called 
high-  or  medium-  and  low-pressure,  respectively.  The  first 
uses  acetylene  under  a  pressure  as  high  as  6  pounds  per  square 
inch  at  the  torch,  while  the  other  uses  a  pressure  of  only  about 
as  many  ounces.  The  torches  for  these  two  systems  are  entirely 
different  in  construction,  and  must  be  handled  differently  in 
operation.  Care  must  be  taken  to  follow  the  instructions  of 
the  manufacturers  in  regard  to  their  operation  in  every  case  or 
satisfactory  results  will  not  be  obtained. 

Impurities  in  Calcium  Carbide.  —  Calcium  carbide,  being 
made  of  coal,  or  coke,  and  lime  by  heating  them  together  in  an 
electric  furnace,  naturally  contains  some  of  the  impurities  in 
these  substances.  Neither  coal  nor  coke  is  free  from  sulphur,  nor 
is  lime  entirely  free  from  phosphorus;  therefore,  acetylene  made 
in  a  generator  will  contain  more  or  less  sulphuretted  hydrogen 
and  phosphoretted  hydrogen,  the  amount  depending  upon  the 
purity  of  the  original  materials.  These  impurities,  and  the  ex- 
ceedingly fine  dust  that  is  sometimes  carried  over  with  the  gas, 
give  to  the  welding  flame  a  somewhat  yellow  color  which  is  not 
noticed  when  dissolved  acetylene  is  used,  the  flame  then  having 
a  slight  violet  tinge. 

The  presence  of  these  sulphur  and  phosphorus  compounds 
can  be  shown  by  a  very  simple  test.  Moisten  a  piece  of  white 
blotting  paper  with  a  lo-per-cent  solution  of  nitrate  of  silver 
and  turn  a  jet  of  acetylene  on  it.  If  these  gases  are  present, 
the  moistened  spot  will  turn  black,  and  a  rough  idea  may  be 
obtained  of  the  amount  of  the  impurities  by  the  rapidity  with 
which  the  action  takes  place.  Inasmuch  as  both  sulphur  and 
phosphorus,  when  present  in  more  than  very  slight  amounts,  are 


WELDING   EQUIPMENT 


injurious  to  iron  and  steel,  it  is  necessary  to  provide  for  the  re- 
moval of  these  gases  from  acetylene,  if  important  welds  are  to 
be  made.  The  importance  of  purifying  generator  acetylene  is 
not  realized  in  this  country,  although  both  in  England  and  on 
the  Continent  purifiers  are  in  quite  general  use.  They  are  of 
comparatively  simple  construction,  and  it  is  believed  that  it  is 
only  a  question  of  time  until  their  use  will  be  general  in  the 
United  States.  On  the  other  hand,  however,  the  carbide  made 


MOTOR  TO  BUN C 


3I,ii-Jiinrry 


Fig.  16.   Davis-Bouraonville  Acetylene  Generator 

in  the  United  States  is  more  free  from  sulphur  and  phosphorus 
compounds  than  that  made  abroad.  Sulphur  and  phosphorus 
compounds  are  not  so  injurious  to  other  metals  as  to  iron  or  steel, 
and,  as  the  quantities  are  small  when  good  carbide  is  used, 
ordinary  work  is  not  seriously  damaged. 

The  dust  carried  over  with  the  gas,  in  certain  types  of  gen- 
erators, consists  very  largely  of  lime,  which  has  an  exceedingly 
injurious  effect  on  any  steel  or  iron  weld.  A  yellow  deposit  on 


WELDING  EQUIPMENT  41 

the  lime  residue  may  indicate  that  the  generator  has  been  work- 
ing at  too  high  a  temperature,  and,  possibly,  a  dangerous  one. 
It  is  not  often  that  this  is  found. 

Design  of  Generators  for  Acetylene  Gas.  —  Fig.  16  shows 
the  form  of  generator  developed  by  the  Davis-Bournonville 
Co.  for  use  with  its  positive-pressure  (often  erroneously  referred 
to  as  high-pressure)  torches.  In  this  generator  the  carbide 
is  introduced  into  the  hopper  A  through  two  filling  holes  at  the 
top  of  the  generator.  As  acetylene  is  an  extremely  inflammable 
gas,  it  must  be  handled  with  considerable  care.  The  operation 
of  acetylene  generators  has  been  made  the  subject  of  careful 
study  in  the  laboratories  of  the  fire  underwriters.  At  present 
the  rules  of  the  insurance  companies  require  a  generator  to  be 
operated  under  such  conditions  that  the  gas  will  be  produced  at 
the  rate  of  i  cubic  foot  per  pound  of  carbide  per  hour.  As  a 
result,  means  must  be  provided  for  dropping  the  calcium  carbide 
from  the  hopper  A  into  the  water  in  the  generator  at  a  prescribed 
rate.  This  is  accomplished  by  means  of  a  clock  motor  which  is 
driven  by  the  counterweight  B.  This  motor  causes  the  rotation 
of  a  disk  at  the  bottom  of  the  hopper,  and  as  the  disk  revolves 
the  carbide  is  swept  off  by  an  inclined  plate  or  vane. 

With  acetylene  gas  under  pressure  of  more  than  two  atmos- 
spheres  —  approximately  30  pounds  per  inch  —  there  is  danger 
of  endo thermic  explosion;  and,  to  provide  an  adequate  margin 
of  safety,  the  pressure  of  the  gas  in  the  generator  is  not  allowed 
to  exceed  15  pounds  per  square  inch.  When  the  pressure  reaches 
1 5  pounds  per  square  inch,  the  first  one  of  these  two  diaphragms 
is  distended,  with  the  result  that  a  locking  device  stops  the  clock 
motor  and,  hence,  cuts  off  the  supply  of  calcium  carbide.  As 
a  safety  device,  a  second  flexible  diaphragm  is  provided  which 
operates  at  a  pressure  slightly  above  15  pounds  per  square  inch. 
In  case  the  first  diaphragm  should  fail  to  work,  the  second  one 
would  rise  and  engage  a  locking  clutch  which  stops  the  motor. 
In  addition,  a  safety  valve  is  provided  at  C  which  will  blow  off 
in  the  event  of  the  pressure  rising  above  the  required  point. 
This  safety  valve  is  connected  to  a  pipe  which  extends  up  above 
the  roof  of  the  generating  house  so  that  the  acetylene  may  be 


ft* 


WELDING  EQUIPMENT  43 

discharged  into  the  atmosphere.  In  this  way,  all  danger  of 
explosion  is  eliminated. 

Lump  carbide,  designated  as  the  ij  by  f  inch  size,  is  used 
in  the  generator.  When  this  carbide  is  dropped  from  the  hopper, 
it  sinks  to  the  bottom  of  the  water  in  the  generator,  and,  as  a 
result,  the  acetylene  gas  which  is  liberated  must  rise  through  the 
full  depth  of  water.  Two  advantages  are  secured  in  this  way: 
first,  the  acetylene  receives  a  preliminary  washing  in  the  gener- 
ator; and  second,  the  heat  produced  by  the  chemical  reaction 
of  the  carbide  with  the  water  is  absorbed  by  the  water  so  that  the 
gas  is  passed  on  at  a  relatively  low  temperature.  Upon  leaving 
the  generator,  the  gas  passes  into  the  pipe  D,  which  carries  it 
to  the  bottom  of  the  flash-back  chamber  E.  This  chamber  is 
full  of  water  and  serves  the  double  purpose  of  giving  the  gas  a 
second  washing  and  forming  a  water  seal  between  the  service 
pipe  and  the  acetylene  in  the  generator.  After  passing  through 
the  flash-back  chamber,  the  gas  enters  the  filter  F,  which  is 
filled  with  mineral  wool  that  serves  to  remove  suspended  impuri- 
ties, and  upon  leaving  this  chamber  the  gas  enters  the  service 
pipe  G,  from  which  connection  is  made  direct  to  the  torches. 
It  is  not  within  the  scope  of  this  treatise  to  give  instructions 
regarding  the  operation  of  the  acetylene  generator,  but  the 
manufacturers  issue  a  booklet  in  which  complete  information 
is  given  in  regard  to  this  branch  of  the  welding  and  cutting 
industry. 

The  generators  are  made  in  five  sizes,  with  capacities  for 
charges  of  25,  50,  100,  200,  and  300  pounds,  respectively.  One 
pound  of  carbide  will  produce  4!  cubic  feet  of  acetylene,  so  that 
the  different  sizes  of  generators  will  produce  112,  225,  450,  900, 
and  1350  cubic  feet  of  acetylene  from  a  single  charge.  These 
generators  are  intended  for  use  in  shops  where  the  acetylene  is 
used  direct  from  the  generator,  but  the  Davis-Bournonville  Co. 
also  makes  a  generator  known  as  the  "Navy"  type,  which  is 
designed  for  use  in  connection  with  a  compression  plant  for 
collecting  the  acetylene  in  cylinders  for  portable  use,  and  acety- 
lene can  also  be  taken  direct  from  the  generator  under  pressure 
for  use  in  the  cutting  and  welding  torches.  In  this  type  of 


44 


WELDING   EQUIPMENT 


plant  provision  is  made  for  drying  the  acetylene  and  removing 
the  air  from  it  preparatory  to  compression. 

Portable  Generators.  —  The  generators  which  have  just  been 
described  are  made  for  installation  in  a  fixed  position,  but  for 
some  classes  of  work  it  is  desirable  to  be  able  to  move  the  source 
of  acetylene  about  from  place  to  place.  To  meet  this  require- 


Fig.  19.   Oxweld  Low-pressure  Acetylene  Generator 

ment,  portable  outfits,  as  shown  in  Figs.  17  and  18,  are  made. 
In  one  of  these  a  two-wheeled  truck  is  employed,  on  which  are 
mounted  an  oxygen  cylinder  and  a  cylinder  containing  the  acety- 
lene gas.  In  the  other  style  of  portable  outfit  an  acetylene 
generator  and  a  battery  of  oxygen  cylinders  are  mounted  on  a 
four-wheeled  truck.  This  equipment  is  made  with  either  the 
25-  or  5o-pound  acetylene  generator,  and  with  a  corresponding 
number  of  oxygen  cylinders,  according  to  the  requirements  of 


WELDING   EQUIPMENT  45 

the  plant  in  which  it  is  to  be  used.  It  is  often  found  convenient 
to  use  one  of  these  portable  outfits  in  order  to  avoid  the  necessity 
of  moving  heavy  work,  or  for  working  in  different  places  in  large 
factories,  where  it  is  easier  to  take  the  torch  to  the  work  than 
to  bring  the  work  to  the  torch. 

Fig.  19  shows  the  generator  furnished  by  the  Oxweld  Acety- 
lene Co.  This  is  a  low-pressure  generator,  used  in  connection 
with  the  company's  low-pressure  torch.  The  illustration,  with 
the  arrows  indicating  the  flow  of  the  gas,  shows  clearly  the  action 
of  the  generator.  The  apparatus  to  the  left  is  the  generator 
proper,  while  that  to  the  right  is  the  gasometer  which  is  used 
for  storing  the  gas  at  low  pressure. 

British  Types  of  Acetylene  Generators.  —  Fig.  20  shows  the 
form  of  generator  developed  by  the  Thorn  &  Hoddle  Acetylene 
Co.  It  is  of  the  water-to-carbide  type  and  is  made  in  three 
different  patterns.  The  generator  consists  of  a  main  water 
tank  in  which  floats  a  gas-holder  guided  by  standards.  The 
generating  chambers  are  surrounded  by  a  large  body  of  water 
and  the  gas  is  generated  at  a  low  temperature.  The  supply  of 
water  is  automatic,  the  rising  and  falling  of  the  gas  bell  closing 
and  opening  a  ball  valve  controlling  the  water  supply.  The 
larger  sizes  of  generators  have  two  or  three  generating  chambers, 
and  the  water  supply  valves  are  so  arranged  that  only  one 
chamber  comes  into  action  at  a  time,  but,  when  this  is  exhausted, 
another  chamber  comes  into  action  without  loss  of  gas  or  stop- 
page of  work,  and  the  exhausted  chamber  may  be  safely  re- 
charged. An  indicator  placed  outside  the  generator  shows  the 
generating  chamber  in  use.  The  gas  is  efficiently  washed,  and  the 
carbide  containers  are  so  constructed  that  the  water  does  not  drip 
onto  the  carbide,  but  rises  towards  it.  The  carbide  used  in  the 
generators  is  "lump,"  designated  as  i  to  i\  inches  or  larger. 
The  gas-holders  and  water  tanks  are  constructed  of  strong 
galvanized  steel. 

The  generators  are  made  in  six  sizes,  with  capacities  for 
charges  of  6,  9,  15,  35,  50,  and  75  pounds,  respectively.  The 
approximate  acetylene  output  of  the  different  sizes  is  27,  42, 
70,  1 60,  230,  and  350  cubic  feet  from  a  single  charge.  The  gen- 


WELDING   EQUIPMENT 


erators  are  made  for  fixed  installations,  or,  as  it  is  desirable  in 
some  classes  of  work  to  move  the  acetylene  source  from  place 
to  place,  portable.  The  portable  equipment  is  made  with  either 
the  9,  15,  35,  50,  or  75  pounds'  generator. 

Fig.  21  shows  a  generator  furnished  by  the  Sirius  Autogenous 
Co.     This  is  a  carbide-to-water  generator.     The  plant  comprises 


Fig.  20.  The  "Incanto"  Acetylene  Generator 

the  following  parts:  Generator,  condenser,  washer,  gasometer, 
and  purifier.  The  generator  consists  of  a  cylindrical  chamber, 
the  upper  portion  containing  the  carbide  magazine  and  automatic 
feed  mechanism,  the  lower  portion  containing  the  generating 
water.  The  carbide  is  distributed  by  a  bucket  wheel,  which  may 
be  automatically  rotated  by  the  falling  of  the  gasometer  bell. 


48  WELDING   EQUIPMENT 

The  condenser  is  provided  to  intercept  humidity.  The  washer 
serves  to  absorb  certain  impurities  and  also  to  prevent  the  gas 
returning  from  the  gasometer  to  the  generator.  A  purifier 
and  filter  are  provided  to  deal  with  the  chemical  impurities  and 
solid  particles.  The  illustration  shows  clearly  the  action  of  the 
generator. 

Hydrogen  Gas.  —  Instead  of  using  oxygen  and  acetylene, 
oxygen  and  hydrogen  are  the  gases  frequently  used  when  cutting 
metals.  In  fact,  for  the  cutting  of  very  thick  steel,  hydrogen 
is  far  superior  to  acetylene,  because  of  the  much  longer  flame  of 
hydrogen.  This  gas  is  obtained  when  water  is  decomposed  by 
electrolysis,  there  being  two  parts  of  hydrogen  to  one  part  of 
oxygen.  The  gas  is  actually  formed  as  a  by-product  in  the 
production  of  oxygen  by  the  electrolytic  method.  It  is  highly 
inflammable  and  produces  a  heat  of  about  4100  degrees  F.  when 
burned  with  oxygen.  In  cutting  steel,  it  leaves  a  comparatively 
smooth  surface,  the  metal  being  but  little  affected  by  oxidiza- 
tion on  either  side  of  the  cut.  For  rapid  and  economic  welding 
the  oxy-acetylene  flame  is  far  superior  to  the  oxy-hydrogen 
flame,  but,  for  cutting  especially  thick  metal,  the  hydrogen 
flame  is,  as  mentioned,  preferable. 

For  welding,  hydrogen  is  only  used  in  localities  where  oxygen 
is  electrolytically  produced  and  the  hydrogen  is  thus  a  by-prod- 
uct. Practical  experience  indicates  that  oxy-hydrogen  welding 
is  suitable  for  thin  sheet  work  only.  The  temperature  of  the 
flame  is  not  sufficiently  high  to  permit  the  welding  of  thick 
plates  or  castings,  since  the  flame  must  be  applied  for  so  long 
a  period  before  the  necessary  fusion  temperature  is  reached, 
that  the  metal  operated  upon  deteriorates.  For  thin  sheet 
welding,  the  process  has  certain  advantages,  however,  as  the 
flame  is  more  diffused  than  the  oxy-acetylene  flame,  and,  conse- 
quently, less  liable  to  melt  through  or  pierce  the  metal,  as  some- 
times occurs  when  the  oxy-acetylene  flame  is  employed  on  thin 
work.  In  fact,  it  is  stated  by  some  welders  that  a  better-looking 
and  more  highly  finished  job  can  be  made  with  the  oxy-hydrogen 
flame  on  sheets  -jV  mcn  and  less  in  thickness,  than  by  any  other 
process  of  welding.  Even  at  best,  however,  the  quality  of  the 


WELDING  EQUIPMENT  49 

weld  is  uncertain,  and  unless  hydrogen  is  produced  as  a  by- 
product its  use  is  expensive. 

City  Gas  for  Welding.  —  Owing  to  the  impurities  present  in 
ordinary  city  gas,  it  cannot  be  employed  for  welding  in  any  case 
where  the  strength  of  the  weld  is  of  importance.  The  flame 
temperature  is  also  considerably  lower  than  the  oxy-hydrogen 
flame;  hence,  this  kind  of  gas  can  be  used  only  on  very  thin 
iron  or  steel  sheets,  or  on  metals  having  very  low  melting  points. 
It  is  not  used  except  in  very  special  cases.  There  are  a  number 
of  other  gases  which  will  burn  when  mixed  with  oxygen,  such  as 
Pintsch  gas,  Blau-gas,  etc.,  but  none  of  these  will  produce  as 
high  a  flame  temperature  as  acetylene. 

Piping.  —  Acetylene  piping  should  be  carefully  designed, 
especially  in  regard  to  size.  Frequently  trouble  is  caused, 
particularly  in  the  case  of  low-pressure  systems,  by  having  the 
pipe  too  small.  The  manufacturers  of  the  equipment  will  give 
advice  in  this  connection.  Acetylene  piping  can  be  put  together 
with  ordinary  screw  joints  and  pipe  grease;  or  other  lubricants, 
such  as  red  or  white  lead,  may  be  used.  It  is  better,  however, 
to  weld  the  pipe  and  insure  in  this  way  against  leakage.  In  the 
case  of  oxygen  piping,  no  grease  or  oil  whatever  should  be  used, 
if  it  is  put  together  with  screw  joints.  A  lubricant  should  not  be 
depended  upon  to  make  a  pipe  joint  in  any  case,  but  only  to  allow 
the  threads  to  be  easily  screwed  into  place;  the  joint  should 
depend  on  the  threads.  Soap  answers  the  purpose  for  oxygen 
pipe  very  well.  It  is,  however,  advisable,  as  in  the  case  of  acety- 
lene piping,  to  weld  the  joints.  Piping  for  both  oxygen  and 
acetylene  should  be  galvanized.  The  ends  of  all  pipes  should 
be  reamed  out  to  make  the  pipe  of  uniform  size  throughout. 
Where  piping  is  welded,  no  fittings  should  be  used.  Valves 
should  be  of  the  best  quality  and  of  sufficiently  large  area,  par- 
ticularly with  a  low-pressure  system,  to  avoid  reducing  the  pres- 
sure. After  the  piping  is  all  erected,-  it  should  be  tested  to  at 
least  100  pounds'  pressure  per  square  inch,  and  leaks,  if  any, 
stopped.  The  best  method  of  testing  is  with  soapsuds,  brushed 
not  only  on  the  joints,  but  all  over  the  pipe,  as  there  are  sometimes 
pin  holes  or  slight  defects  in  the  body  of  the  pipe. 


50  WELDING  EQUIPMENT 

Acetylene  and  Oxygen  Tanks.  —  Portable  acetylene  tanks 
are  provided  by  the  makers  of  acetylene  gas,  from  whom  they 
may  be  obtained  on  reasonable  terms.  The  cost  of  the  gas  is 
about  two  and  one-half  times  that  made  in  a  generator,  but  this 
expense  is  warranted  in  some  cases  even  for  shop  work,  on  account 
of  the  tanks  costing  less  than  the  generator.  Each  case  has  to 
be  considered  separately.  The  larger  the  shop,  the  greater  is  the 
advantage  in  the  use  of  a  generator.  The  charging  pressure  of 
these  tanks  is  about  225  pounds  per  square  inch,  but  this  varies 
so  much  with  the  temperature  that  the  pressure  alone  is  no  in- 
dication of  the  amount  of  gas  in  the  tank.  It  is  sometimes 
found  that,  after  working  an  hour  or  so,  the  pressure  is  equal  to 
or  greater  than  that  at  the  start,  due  to  the  tank  being  warmer. 
Tanks  should  be  kept  in  a  cool  place  and  the  outlet  capped  to 
be  sure  that  there  is  no  chance  for  a  leak. 

Compressed  acetylene  should  never  be  used  at  a  greater  rate 
per  hour  than  one-seventh  of  the  capacity  of  the  tank.  For 
instance,  if  a  tank  holds  300  cubic  feet,  45  cubic  feet  per  hour 
is  about  the  maximum  rate  at  which  the  acetylene  should  be 
drawn.  If  it  is  necessary  to  use  a  torch  large  enough  to  exceed 
this  rate,  two  or  more  tanks  should  be  coupled  together  with 
manifolds,  which  can  be  procured  from  the  manufacturers  of  the 
•tanks  or  made  in  any  good  machine  shop.  A  greater  rate  of 
discharge  than  that  stated  above  results  in  some  of  the  acetone 
being  drawn  out,  which  is  liable  to  cause  bad  welds. 

The  Federal  law  requires  that,  in  shipping  a  tank  containing 
oxygen,  or  a  full  acetylene  tank,  a  label  be  pasted  on  it,  colored 
green  or  red,  respectively,  and  worded  according  to  the  instruc- 
tions on  the  subject  issued  by  the  Bureau  of  Explosives,  30 
Vesey  St.,  New  York  City,  from  which  copies  may  be  obtained. 
Empty  oxygen  tanks  need  no  label,  but  the  bill  of  lading  or 
express  receipt  should  specify  that  the  tanks  are  empty,  in  order 
to  obtain  the  advantage  of  the  lower  freight  rate.  Empty  acety- 
lene tanks  must  have  the  red  label  removed  before  shipment  and 
can  only  be  shipped  by  freight.  Any  tank  found  to  be  defective 
should  be  tagged  and  the  manufacturers  notified  by  letter.  It 
occasionally  happens  that  a  valve  cannot  be  shut.  Such  a  matter 


WELDING  EQUIPMENT  51 

should  be  reported  to  the  manufacturers,  and,  if  the  valve  is 
found  defective,  they  will  make  an  adjustment  for  the  amount 
of  gas  lost.  All  tanks,  both  oxygen  and  acetylene,  are  provided 
with  safety  disks  or  plugs.  These  are  intended  to  prevent  exces- 
sive pressure  caused  by  heat  or  otherwise,  by  allowing  the  gas 
to  escape  gradually  and  thus  prevent  an  explosion.  In  some 
cases  these  safety  devices  are  so  arranged  that  they  are  sealed 
to  prevent  tampering  with  them.  If  this  seal  is  broken,  no 
adjustment  will  be  made.  Therefore,  if  anything  goes  wrong 
with  the  valve  or  disk,  do  not  attempt  to  repair  it,  but  return 
it  in  exactly  the  condition  in  which  it  was  found.  Of  course, 
if  an  acetylene  tank  should  leak,  it  should  be  placed  out  of  doors 
to  avoid  danger  of  explosion.  The  percentage  of  such  diffi- 
culties is  exceedingly  small. 

Machine  Tool  Equipment  for  Welding  Shops.  —  The  machine 
tool  equipment  to  be  provided  will  depend  upon  circumstances. 
For  a  shop  where  welding  alone  is  done,  the  following  should 
be  provided:  24-inch  upright  drill;  floor  stand;  two-spindle 
emery  wheel  for  lo-inch  wheels;  flexible  shaft  grinder  with 
6-inch  wheel.  These  tools  can  be  driven  by  a  small  electric 
motor,  if  current  is  available.  Any  other  motive  power  can  be 
used,  although  a  gasoline  engine  should  be  carefully  installed 
in  order  to  avoid  fire  risk.  It  is  best  not  to  permit  gasoline  in 
the  shop  under  any  pretext  whatever. 

For  a  large  shop,  or  where  a  good  machine  shop  is  not  available, 
it  may  be  necessary  to  install  more  machinery.  The  following 
additional  tools  will  cover  practically  everything  necessary: 
lathe,  20-inch  swing,  4  feet  between  centers;  lathe,  30-inch 
swing,  8  feet  between  centers;  planer,  36  by  36  inch  by  6  feet; 
pillar  shaper,  1 2-inch  stroke;  horizontal  boring  mill,  4  feet 
between  heads;  3-foot  plain  radial  drill.  These  tools  must  be 
accurate,  but,  as  there  is  no  question  of  production  in  quantity 
involved,  they  may  be  of  light  and  simple  construction;  for 
instance,  it  is  not  necessary  to  have  quick  change-gears  on  the 
lathes.  All  such  expense  should  be  avoided.  Careful  con- 
sideration should  be  given  to  the  machine  tool  equipment.  It 
is  expensive,  and,  unless  enough  work  is  done,  it  will  not  pay 


52  WELDING  EQUIPMENT 

to  install  it,  but  it  will  be  cheaper  to  do  the  work  with  hand 
tools,  or  even  send  it  to  a  shop  at  some  distance. 

The  real  cost  of  operating  a  machine  is  frequently  under- 
estimated. Interest,  depreciation,  repairs,  insurance,  and  taxes 
have  to  be  paid,  even  if  not  charged  in  the  operating  expenses. 
Taking  the  sum  of  these  items  at  1 5  per  cent  per  year  on  the  cost 
of  a  machine,  and  assuming  the  installed  cost  at  $2000,  there 
will  be  a  monthly  expense  of  $25  against  the  machine.  If  it 
is  operated  200  hours  per  month,  the  hourly  expense  will  be 
i2§  cents;  if  it  is  used  only  20  hours  per  month,  the  hourly  ex- 
pense will  be  $1.25.  It  is  evident  that  no  ordinary  charge  for 
work,  say  60  or  75  cents  per  hour,  will  cover  the  latter  expense, 
which  is  exclusive  of  labor,  power,  and  supplies.  Each  case  is 
a  law  in  itself,  and  all  that  is  urged  is  that  careful  and  intelligent 
consideration  be  given,  so  as  to  avoid  financial  loss. 

Other  Equipment.  —  It  is  generally  necessary  to  heat  pieces 
before  welding,  to  obtain  a  sound  weld,  as  well  as  to  economize 
in  the  gases.  For  this  purpose,  plain  blacksmith  forges  are  the 
most  convenient  for  small  work.  The  tuyere  should  be  level  with 
the  bottom  of  the  pan,  which  should  be  of  cast  iron.  The  pan 
should  measure  about  23  by  36  inches  inside  and  about  4  inches 
deep,  which  will  allow  the  bottom  to  be  lined  with  i-inch  thick 
firebrick,  laid  in  fireclay,  and  still  leave  the  sides  high  enough  to 
keep  the  fire  off  the  floor.  The  simplest  fan  drive  is  good  enough, 
as  it  is  never  used  except  in  starting  the  fire.  It  is  well  to  have 
plenty  of  forges,  as  a  good  welder  on  moderate-sized  work  can 
keep  two  or  three  busy  without  any  difficulty. 

Floors.  —  For  heavy  work  a  concrete  or  brick  floor  is  neces- 
sary; this,  if  of  concrete,  should  be  at  least  6  inches  thick,  laid  on 
a  solid  foundation  of  cinders  that  should  be  free  from  coal  and 
well  rammed;  and  proper  provision  should  be  made  for  drainage. 
The  concrete  may  be  a  rather  lean  mixture,  but  should  have  a 
top  dressing  ^  inch  thick  of  a  rich  cement  mortar.  The  floor 
should  be  about  10  by  15  feet  or  12  by  12  feet,  preferably  the 
former,  as  it  is  more  convenient  for  a  number  of  fires. 

Hoists.  —  Over  the  floor  should  be  some  kind  of  hoist  of  a 
capacity  of  about  3  tons,  which  will  handle  almost  any  work 


WELDING  EQUIPMENT  53 

_ 

that  can  be  brought  into  the  shop.  The  kind  of  hoist  depends 
upon  the  circumstances,  such  as  the  construction  of  the  building, 
space  around  the  floor,  etc.  A  jib  crane  is  very  convenient, 
but  expensive.  If  the  roof  trusses  are  strong  enough,  an  I-beam 
extending  between  them  and  carrying  a  trolley  and  chain  hoist 
is  ample  and  cheap. 

Provision  for  Building   Preheating   Fires.  —  If   the   floor  of 
the  building  is  of  concrete,  be  sure  that  it  is  heavy  enough  to 


Fig.  22.    Welding  Table,  Welding  Jig,  and  V-blocks 

stand  considerable  heat.  Of  course,  a  fire  should  never  be  built 
directly  on  the  concrete.  A  layer  of  firebrick  can  be  placed  under 
the  entire  area  to  be  covered  by  the  fire,  and  the  piece  laid  on  this 
raised  enough  to  get  the  fire  in  place;  or  plates  of  cast  iron  or 
steel  can  be  laid  on  bricks  to  give  air  space  underneath  and  the 
fire  built  on  the  plates.  Cast-iron  plates  i  by  3  feet  are  best. 
They  should  have  i-inch  holes  cored  in  them  about  6  inches 
apart  for  draft,  and,  when  setting  up,  they  should  be  left  slightly 
apart  for  the  same  reason.  Angle-plates  of  the  same  general 
design  may  be  used  for  walls  instead  of  bricks,  and  in  some  cases 
are  very  convenient.  They  should  not  have  any  holes  in  them. 


54  WELDING  EQUIPMENT 

They  radiate  more  heat  than  bricks,  but  do  not  fall  over  so  easily. 
Some  of  them  should  be  18  inches  long  for  small  fires.  Fire- 
brick will  also  be  needed  for  holding  the  fires  in  place  on  the 
forges,  and  for  use  on  the  floor.  Hard-burned  brick,  while  not 
so  good  for  the  regular  purposes  for  which  firebrick  is  used,  is 
better  for  this  purpose,  as  it  does  not  break  or  chip  so  easily  in 
handling. 

Welding  Table.  —  Fig.  22  shows  a  cast-iron  table  30  inches 
wide  and  72  inches  long.     It  is  planed  on  the  top,  bottom,  and  all 


Fig.  23.   Another  View  of  Welding  Table  and  Angle-plate 

edges,  and  has  a  support  made  of  old  } -inch  pipe  welded  together. 
It  is  26  inches  high  from  the  floor,  which  is  found  to  be  most 
convenient,  as  small  work  can  be  done  by  the  welder  while 
sitting;  and  for  large  work,  such  as  rear  axles,  rear-axle  housings, 
cylinders,  etc.,  which  have  to  be  tested,  and  which  are  frequently 
set  up  high  on  blocking,  it  is  not  too  high  for  convenience.  An- 
other view  of  the  table  is  shown  in  Fig.  23,  which  also  shows  an 
angle-plate  that  is  very  convenient.  It  will  be  noticed  that  the 
rib  D,  which  is  f  inch  thick,  extends  on  two  sides  of  the  table, 
while  the  other  two  sides  are  provided  with  a  flange  B.  As 


WELDING  EQUIPMENT  55 

stated,  all  of  these  edges  are  planed.  This  permits  of  clamping 
pieces  vertically  or  horizontally,  as  the  case  may  be,  and  has 
been  found  to  be  an  exceedingly  convenient  arrangement. 

Jigs  and  V-blocks.  —  Fig.  22  also  shows  what  was  originally 
designed  as  a  jig  for  welding  crankshafts,  although  it  has  been 
found  that  it  is  a  valuable  appliance  for  many  other  purposes, 
particularly  in  welding  bars,  tubing,  etc.,  that  must  be  kept 
straight.  It  is  shown  at  C.  The  V-blocks  are  provided  with 
tongues  which  slide  in  the  groove  D;  'the  slots  E  and  F  are  at 
unequal  distances  from  the  groove.  This  is  done  to  insure 
proper  setting  of  the  V-blocks.  The  base  is  planed  on  the  top 
and  bottom,  and  after  the  bases  of  the  V-blocks  were  machined 
they  were  bolted  in  place  and  the  V's  in  the  top  of  them  planed 


Fig.  24.   Set  of  Cast-iron  V-blocks  of  Different  Thicknesses 

at  the  same  time  to  insure  absolute  alignment.  The  V-block 
caps  have  the  holes  for  the  studs  drilled  J  inch  large,  so  that  there 
will  be  no  difficulty  in  clamping  when  screwed  down  on  a  round 
piece.  The  base  of  this  jig  is  10  inches  wide  and  36  inches 
long.  The  V-blocks  are  of  different  thicknesses,  the  wide  ones 
being  2\  inches  and  the  narrow  ones  i|  inch.  This  permits  of 
getting  into  corners,  which  is  sometimes  desirable.  There  are 
also  shown  a  plate  of  graphite  at  A  and  a  set  of  ordinary  V- 
blocks  at  B,  which  are  better  shown  in  Fig.  24.  Two  sets  of 
these  are  useful  for  holding  shafts  and  similar  pieces  that  must 
be  kept  straight  in  welding,  and  will  be  found  of  advantage  for 
many  other  purposes.  The  six  V-blocks  should  be  made  from 
one  casting,  first  planed  and  then  cut  off  to  the  required  thick- 
ness. Each  one  of  a  pair  should  be  planed  to  the  same  thickness, 
and  the  i-  and  i|-inch  sizes  together  should  have  the  same  thick- 


WELDING  EQUIPMENT 


ness  as  the  2|-inch  size.  The  grooves  should  be  planed  in  the 
casting  before  cutting  off,  to  enable  the  blocks  to  be  placed  in  the 
same  line  as  when  originally  planed,  it  being  difficult  otherwise 
to  plane  the  V's  exactly  symmetrical.  The  various  devices 
shown  in  these  two  illustrations  make  it  possible  to  take  care 
of  almost  any  shape  that  must  be  kept  square  or  in  line. 

A  kerosene-oil  burner  can,  in  many  cases,  be  used  for  heating 
large  articles  in  which  contraction  strains  will  not  cause  any 
trouble,  and  is  useful  to  have  in  a  welding  shop. 


Fig.  25.   Rack  for  Mandrels,  Blocking,  and  Other  Tools 

Rack  for  Bars  and  Mandrels.  —  The  general  tendency  in  a 
shop  of  any  kind  is  to  allow  bars,  mandrels,  or  similar  material 
to  lie  around  in  corners  or  under  the  bench,  where  they  are  diffi- 
cult to  reach  and  frequently  damaged.  A  rack  for  such  parts, 
shown  in  Fig.  25,  is  safer,  and  improves  the  appearance  of  the 
shop.  This  rack  is  about  5  feet  long  and  3  feet  high,  and  is  made 
out  of  old  f -inch  pipe  welded  together.  On  the  right-hand  end 
is  shown  a  device  which  in  its  different  forms  is  frequently  of 
service  in  preventing  the  melting  of  babbitt  bearings.  It  cannot 
be  used  in  all  cases,  but,  where  there  is  much  work  of  one  kind  to 


WELDING  EQUIPMENT  57 

be  done,  it  pays  to  use  it.  This  particular  device  consists  of 
cold-drawn  steel  tubing  about  £  inch  thick  and  of  proper  outside 
diameter  to  fit  the  bearings  of  the  Ford  automobile  cylinder 
block.  When  it  is  necessary  to  do  any  welding  on  one  of  these 
cylinders,  this  piece  is  clamped  into  the  bearings,  just  tight  enough 
so  that  it  will  not  turn  readily,  and  filled  with  water.  The  ends 
shown  hanging  down  stand  up  straight.  Any  change  in  the 
position  of  the  cylinder  in  the  fire  can  be  taken  care  of  by  keeping 
the  legs  upright.  It  is  necessary  to  watch  the  water  carefully 
so  that  it  does  not  evaporate. 


Fig.  26.   Pipe  Mandrel  used  to  prevent  Melting  of  Babbitt  Bearings 

Cooling  Device  for  Babbitt  Bearings.  —  Fig.  26  shows  the  use 
of  this  cooling  apparatus.  The  illustration  shows  the  device 
held  in  place  by  wires.  This  was  found  at  the  first  trial  to  be 
unsatisfactory,  as  it  did  not  hold  the  pipe  in  contact  with  the 
bearings  closely  enough,  and  at  the  present  tune  bolts  and  J- 
inch  pieces  of  steel  are  used  to  overcome  the  trouble. 

Miscellaneous  Equipment.  —  A  substantial  work-bench  with 
one  or  two  vises  should  be  provided.  If  two  vises  are  provided, 
one  vise  should  have  jaws  5  inches  wide,  for  general  use;  the 
other  may  be  a  second-hand  one,  to  be  used  for  holding  pieces 


58  WELDING  EQUIPMENT 

while  welding,  when  they  cannot  be  easily  blocked  up  so  that 
the  welder  can  reach  all  parts  of  the  weld.  The  good  vise  should 
never  be  used  for  welding,  as  the  heat  will  in  the  course  of  time 
draw  the  temper  of  the  jaws.  The  total  number  of  vises  and 
the  size  and  number  of  benches  required  will  depend  upon  the 
number  of  welders  employed.  For  four  men,  one  old  vise  and 
two  good  ones  will  be  sufficient;  the  bench  may  have  a  length 
of  about  25  feet,  or  three  small  benches  may  be  used.  Several 
pairs  of  "pick-up"  tongs  for  handling  bricks  and  other  hot 
objects,  and  gas  pliers  in  lo-inch  and  1 3-inch  sizes  for  use  around 
the  forges  are  necessary;  their  screw-driver  ends  should  be  ground 
off  or  bent  over  to  make  them  safe  when  lifting  with  the  end 
toward  the  face,  as  the  sharp  end  has  caused  bad  injuries.  As  soon 
as  the  jaws  become  slippery,  the  pliers  should  be  thrown  away. 

Refractory  Graphite  Mixture.  —  In  many  cases,  especially 
where  the  pieces  are  made  of  cast  iron,  and  heavy,  or  where  lugs 
or  projections  have  to  be  built  higher  than  the  adjacent  surfaces, 
tune  will  be  saved  by  building  a  dam  of  some  refractory  material 
of  the  proper  shape  and  melting  the  metal  into  it.  The  best 
material  for  this  in  the  case  of  cast  iron  or  steel  is  a  graphite 
mixture,  such  as  is  used  in  crucibles.  This  can  be  obtained  in 
blocks  of  any  size  and  shape,  by  ordering  it  specially;  but 
rectangular  blocks  from  |  inch  thick  and  up,  and  round  rods 
of  various  diameters,  for  use  in  keeping  holes  from  filling  up, 
are  stock  sizes,  and  can  be  obtained  on  short  notice  from  crucible 
manufacturers.  An  assorted  stock  will  be  of  great  aid  in  quick 
work.  In  using  this  material,  it  will  be  found  advisable  to  have 
it  in  position  while  preheating.  It  is  more  or  less  porous,  and, 
when  covered  over  during  the  welding,  the  heated  air  coming 
from  the  pores  will  cause  pin  holes,  as  it  has  no  other  way  to 
escape  than  through  the  weld.  Preheating  the  graphite  expels 
some  of  the  air  and  leaves  less  to  cause  trouble ;  but  if  a  smooth, 
thoroughly  sound  weld  is  required,  it  will  be  necessary  to  turn 
the  piece  over,  remove  the  graphite,  and  melt  the  metal  until 
the  blow-holes  are  eliminated. 

C-clamps  and  Hand  Tools.  —  An  assortment  of  C-clamps, 
with  from  3-  to  lo-inch  opening,  is  needed  for  clamping  work 


60  WELDING  EQUIPMENT 

Asbestos  Paper.  —  Asbestos  building  paper  is  used  to  protect 
the  welder  from  the  heat;  to  confine  the  heat  to  the  piece  being 
heated;  to  keep  drafts  off  a  casting  that  has  been  welded,  which 
without  such  protection  would  tend  to  crack;  and  after  it  has 
been  broken  up  so  small  as  to  be  useless  for  these  purposes,  it 
is  valuable  for  packing  cylinders,  etc.,  to  allow  them  to  cool 
uniformly.  This  material  comes  in  rolls  of  about  100  pounds 
and  in  thicknesses  varying  from  6  to  12  pounds  per  100  square 
feet.  The  8-pound  material  is  heavy  enough  for  general  use. 

Plaster-of-paris  Patterns.  —  Some  knowledge  of  pattern- 
making  is  very  helpful,  especially  where  pieces  of  some  size 
are  missing.  It  is  expensive  to  fill  up  such  places  with  the 
torch.  If  a  pattern  can  be  made  to  fit,  its  use  will  make  a 
cheaper  and  better-looking  job,  particularly  if  the  surface  is 
irregular.  Even  if  the  pieces  are  not  missing,  but  are  many  in 
number  and  small,  so  that  the  total  length  of  welds  would  exceed 
the  length  of  the  weld  required  if  a  single  casting  were  used  for 
the  repair,  it  generally  pays  to  make  one.  Plaster-of-paris  is  the 
most  convenient  material  to  use  for  patterns  for  this  purpose. 
Wooden  patterns  are  very  expensive,  and,  unless  they  are  simple 
and  a  number  of  castings  are  to  be  made,  are  out  of  the  question. 
It  requires  some  experience  to  handle  plaster-of-paris  success- 
fully, and  it  is  impossible  to  lay  down  rules  for  its  use  that  will 
fit  all  cases.  Therefore,  the  following  suggestions  will  not  always 
apply,  and  good  judgment  and  ingenuity  will  have  to  be  used: 

1.  Do  not  mix  the  plaster  too  dry,  or  it  will  set  too  soon. 

2.  Do  not  mix  too  much  at  once,  but  have  several  batches 
ready  to  mix  one  after  another,  if  a  large  quantity  is  needed. 

3.  Prepare  the  piece  by  chipping  or  in  other  ways,  so  that  the 
pattern  will  come  out  easily. 

4.  Make  the  shape  of  the  pattern  as  simple  as  possible,  by 
cutting  out  irregularities  around  the  sides.     The  sum  of  two 
sides  of  a  triangle  is  always  greater  than  the  third  side,  and 
cutting  off  angles,  of  course,  means  a  saving  in  welding. 

5.  Bevel  the  edge  of  a  cast-iron  piece  before  pouring  the 
plaster-of-paris,  and  bevel  the  edge  of  the  pattern  before  taking 
it  out;  it  comes  out  more  easily  and  saves  preparing  the  casting. 


.  1 


62  WELDING  EQUIPMENT 

6.  Do  not  bevel  too  much,  but  leave  enough  so  that  it  can  be 
fitted  tightly  in  place.     This  helps  in  less  contraction  of  the 
weld.     The  fit  need  not  be  perfect,  but  the  better  it  is,  the 
better  the  job  will  be. 

7.  In  the  case  of  aluminum,  fit  well,  but  do  not  bevel  unless 
over  f  inch  thick,  and  then  leave  about  J  inch  bearing,  as  alu- 
minum crushes  easily  when  hot,  and  there  should  be  bearing 
enough  to  force  expansion  without  crushing,  if  possible. 


Fig.  29.   Preheating  Floor  for  Building  Fires 

8.  Have  the  molder  rap  the  pattern  well;  the  shrinkage  of 
cast  iron  in  cooling  is  J  inch  per  foot,  and  of  aluminum  ^  mcn 
per  foot.  In  the  case  of  large  patterns  it  will  be  necessary  to 
add  the  needed  amount  to  the  proper  edges  and  surfaces  to  allow 
for  the  shrinkage,  and  enough  more  to  permit  of  any  finishing 
that  may  be  necessary. 

General  Shop  Arrangement.  —  Fig.  28  shows  the  interior  of 
a  welding  shop.  The  arrangement  is  not  ideal,  because  there 
are  windows  only  on  one  side  of  the  shop,  which  leaves  consid- 
erable floor  space  that  cannot  be  utilized;  but  the  arrangement 
of  the  forges  and  welding  table  should  be  noticed,  particularly 
with  reference  to  the  work-bench.  In  arranging  a  welding  shop, 
the  welding  table  and  forges  should  be  located  near  a  good  light, 


WELDING  EQUIPMENT  63 

preferably  daylight,  so  that  the  lining-up  of  work  can  be  done 
quickly  and  accurately.  Old  carbide  cans  are  used  under  the 
forges  to  catch  the  ashes  from  the  charcoal  fires.  These  cans 
are  kept  partly  filled  with  water  all  the  time.  Before  closing 
at  night,  the  wooden  floor  around  the  forges  is  well  soaked  with 
water. 

The  acetylene  generator  room  A  is  built  in  accordance  with 
the  underwriters'  requirements  and  has  a  standard  fire  door. 
No  light,  except  daylight,  is  permitted  in  the  room,  nor  is  there 
any  opening  except  one  window  and  the  door  into  the  shop. 
It  would  be  preferable  to  have  the  door  opening  from  the  outside 
of  the  building  into  this  room,  but  in  this  case  it  could  not  be 
so  arranged.  The  work  on  the  concrete  floor  shown  in  the  fore- 
ground is  reached  by  the  use  of  long  hose  extending  from  the 
regulating  valves  on  the  wall. 

Fig.  29  shows  the  concrete  floor  on  which  the  heavy  welding 
is  done.  In  certain  cases,  as,  for  instance,  when  a  large  number 
of  cylinders  are  to  be  repaired,  and  the  forges  are  in  use  for  other 
work,  special  fires,  as  shown  at  B,  are  built  on  it.  Of  course 
such  fires  are  not  built  directly  on  the  floor,  but  on  sheet-iron 
or  cast-iron  plates  which  rest  on  bricks.  There  are  four  cylinders 
of  various  sizes  in  the  fire  B.  At  D  is  shown  a  homemade  fur- 
nace lined  with  firebrick  i  inch  thick  on  the  bottom  and  sides, 
which  is  used  for  preheating.  Its  dimensions  are  25  by  21  by 
10  inches,  and  the  top  angle  iron  is  34  inches  from  the  floor. 
A  better  size  is  42  by  21  by  12  inches  deep.  A  furnace  of  these 
dimensions  would  be  large  enough  to  handle  the  largest  "  six- 
in-block"  cylinder  made. 

Fire  Risk.  —  Chlorate  of  potash  and  carbide  are  both  dan- 
gerous from  a  fire  standpoint,  and  should  be  kept  outside  of  the 
shop,  preferably  in  a  shed  separated  entirely  from  the  building. 
Most,  if  not  all,  cities  regulate  the  storage  of  these  chemicals. 
If  possible,  a  shop  location  should  be  selected  away  from  a  bad 
fire  risk,  such  as  a  lumber  yard,  planing  mill,  cabinet  shop,  oil 
store,  etc.,  as  these  automatically  increase  the  insurance  rate  no 
matter  how  well  the  welding  shop  is  protected.  The  installing 
of  automatic  sprinklers  should  receive  careful  consideration, 


64  WELDING  EQUIPMENT 

particularly  with  a  low- roofed  building,  as  the  heat  from  heavy 
welding  fires  is  great.  Overhead  wooden  truss  members  and 
joists  should  have  the  accumulation  of  dust  cleaned  off  at  fre- 
quent intervals,  as  it  is  liable  to  catch  fire  from  charcoal  sparks. 
A  coat  of  whitewash,  using  the  acetylene  generator  residue, 
is  a  good  thing  to  keep  sparks  from  catching,  as  well  as  being  of 
considerable  assistance  in  lighting  the  shop.  Charcoal  fires 
should  be  kept  covered  with  asbestos  paper  to  hold  sparks  down. 
It  should  be  remembered  that  even  if  the  fire  insurance  were 
paid  the  day  after  the  fire,  there  would  be  a  great  loss  from  not 
being  able  to  do  business  and  that,  therefore,  all  precautions 
should  be  taken.  Insurance  should  be  considered  as  a  protection 
against  the  mistakes  of  others,  and  not  as  a  license  to  be  careless. 
If  every  one  would  act  as  if  no  insurance  could  be  collected  for 
damage  caused  by  his  own  carelessness,  there  would  be  fewer 
fires,  and  insurance  rates  would  not  be  as  high  as  they  are. 

Eye  Protection.  —  Dark  glasses  should  always  be  worn  while 
welding,  as  the  eyes  are  liable  to  be  injured,  particularly  by  the 
intense  glare  from  the  flux  used  in  welding  cast  iron.  For  cast 
iron,  very  dark  glasses,  with  a  greenish  tinge,  are  most  suitable. 
For  other  metals,  lighter  colored  glasses  are  better,  as  they  permit 
a  clearer  vision  of  what  is  being  done.  In  any  case,  glasses 
are  dark  enough,  if  immediately  after  welding  it  is  possible  to 
see  clearly  without  being  bothered  with  white  spots  in  front  of 
the  eyes  after  taking  off  the  glasses. 


CHAPTER  II 
PREPARATION    OF   WORK   FOR   WELDING 

IT  is  generally  essential  that  a  weld  be  made  through  the  whole 
section  of  a  break.  Sometimes  this  is  not  necessary,  and  in 
exceptional  cases  it  may  be  impossible;  for  instance,  in  the 
case  of  a  break  through  the  eye  of  a  cast-iron  piece,  where  the 
diameter  of  the  hole  is  small  compared  with  its  length,  it  is  gen- 
erally impossible  to  reach  all  of  the  crack  with  the  torch  from  the 
inside  of  the  hole,  and  there  is  danger  of  producing  hard  spots, 
which  cannot  be  removed  except  with  special  grinding  machinery 
that  is  not  usually  available.  In  such  cases  extra  caution  must 
be  used  to  insure  a  satisfactory  job. 

Beveling  of  Edges.  —  For  ordinary  work,  it  is  sufficient  to 
bevel  the  edges  of  the  broken  parts  so  that  when  placed  together 
the  included  angle  will  be  90  degrees  (see  Fig.  i),  and  so  that  just 
enough  of  the  old  break  will  be  left  to  enable  it  to  be  correctly 
set  up  for  welding.  The  reason  for  opening  the  break  to  a  go- 
degree  angle  is  to  permit  the  flame  of  the  torch  to  reach  the 
bottom  of  the  V,  so  that  the  metal  may  be  melted  thoroughly 
and  the  natural  bridging  effect  of  the  melted  metal,  with  the 
resulting  imperfect  weld,  may  be  avoided.  It  is  not  unusual 
for  even  an  experienced  welder  to  find  such  an  imperfection  in 
one  of  his  welds,  particularly  if  it  is  a  "  rush"  job;  and  it  is  one 
of  the  difficulties  a  beginner  must  carefully  avoid,  particularly 
if  the  piece  can  be  welded  from  one  side  only,  as  is  frequently 
the  case.  In  such  cases  the  crack  must  be  entirely  burned 
through  with  the  torch,  even  if  drops  of  metal  remain  hanging 
under  the  weld.  It  is  especially  important  that  the  go-degree 
angle  be  maintained  in  preparing  steel.  This  metal  sets  so 
rapidly  that  the  bottom  of  the  weld  will  be  full  of  cold  shuts, 
or  a  great  amount  of  time  will  be  lost  and  gases  wasted  in  burn- 
ing away  metal  to  secure  a  good  weld,  unless  the  beginning  of 

65 


66 


PREPARATION   OF   WORK 


the  weld  is  made  easy  to  reach.  It  is  also  advisable  to  have 
plenty  of  room  for  the  flame  to  spread,  in  order  to  avoid  over- 
heating the  head  and  the  tip. 

A  very  good  way  of  preparing  parts  where  there  is  not  suffi- 
cient room  for  a  go-degree  angle,  and  also  for  heavy  welds,  by 
which  a  considerable  saving  of  gases  and  time  may  be  accom- 
plished, is  to  drill  out  the  bottom  of  the  crack  with  a  f-inch 
drill  and  bevel  the  sides  to  less  than  90  degrees.  This  applies 
to  both  steel  and  cast  iron,  and  is  especially  useful  when  the 
break  is  in  a  corner,  where  it  is  evident  that  a  go-degree  angle 
cannot  be  obtained.  This  method  also  frequently  reduces 
the  time  of  preparing  the  work,  as  with  cast  iron  the  remainder 
of  the  V  can  be  easily  removed  with  a  sledge  and  handle  chisel. 


Machinery 


Fig.  1.   Method  of  Welding  Thick  Materials 

Instead  of  beveling  only  from  one  side,  as  in  Fig.  i,  it  is  prefer- 
able to  bevel  the  work  from  both  sides,  when  possible,  resulting 
in  a  double  V,  as  shown  in  Fig.  2.  It  will  be  evident  that  this 
needs  only  half  the  welding  that  a  single  V  does,  besides  which 
it  tends  to  produce  a  better  weld.  A  crack  remaining  in  the 
center  of  a  piece  is  not  nearly  as  dangerous  as  if  it  were  on  the 
outside,  and  the  shallower  the  V,  the  more  readily  is  a  good  weld 
made.  Any  method  of  making  the  V  is  allowable,  the  object 
being  to  open  up  the  V  well,  and  to  permit  of  making  the  best 
and  easiest  weld.  For  small  pieces  of  any  metal,  the  use  of  an 
emery  wheel  is  probably  the  best  method.  Cold  chisels  and 
sledges  or  hammers  are  excellent  for  cast  iron,  where  the  piece 
will  stand  their  use.  In  some  cases  a  hacksaw  is  most  useful. 
Drilling  along  the  crack  and  chipping  out  the  bridges  roughly 
is  a  good  method  where  the  piece  is  cracked  and  not  broken. 
The  drill  should  be  ground  to  an  included  angle  of  the  lips  of 


PREPARATION  OF  WORK  67 

about  120  degrees,  and  the  point  of  the  drill  should  just  go 
through  the  metal.  If  it  goes  too  far,  there  will  be  trouble  on 
account  of  the  bottom  of  the  hole  burning  through  too  quickly, 
especially  if  a  heavy  tip  must  be  used.  The  diameter  of  the  drill 
should  be  about  equal  to  the  thickness  of  the  piece  to  be  welded. 
Welding  Pipe  Fittings.  —  There  is  one  method  which  is  of 
much  assistance  in  such  cases,  for  example,  as  that  of  a  large  pipe 
or  pipe  fitting  flange  broken  off  at  the  root,  where  the  body  of  the 
casting  is  not  very  thick,  say,  f  inch.  A  fitting,  such  as  an  elbow, 
must  be  kept  in  a  fire  to  avoid  cracking  and  is  awkward  to  turn 
while  red  hot,  as  well  as  "  hard"  on  the  welder.  The  part  being 
welded  would  ordinarily  be  above  the  fire  by  an  amount  equal  to 

about   the   diameter  of   the     . 

flange,  which  would  allow  it 
to  cool  rapidly,  making  weld- 
ing difficult  and  probably  re- 
sulting in  a  cracked  casting 
when  cooled.  If,  however, 
the  inside  of  the  crack  be 
chipped  out  to  the  regular  V 
halfway  through,  and  the 

,  J  Fig.  2.   Work  Beveled  from  Both  Sides 

outside  edges  left  nearly  par- 
allel and  about  £  inch  apart,  leaving  a  few  narrow  parts  of  the 
old  crack  to  line  it  up  by,  the  elbow  can  be  set  with  the  flange 
downward  in  the  fire  and  allowed  to  remain  there  until  the  out- 
side is  entirely  welded.  This  is  easily  done  by  playing  the  flame 
between  the  parallel  sides  of  the  crack,  which,  as  they  confine 
the  heat  closely,  soon  become  melted,  and  run  together  at  the 
bottom,  with  careful  handling  of  the  torch;  after  this,  sufficient 
metal  is  added  to  complete  the  outside  of  the  weld.  It  is  then 
an  easy  matter  to  weld  the  inside,  as  the  part  worked  on  can  be 
in  the  fire  all  the  time. 

Welding  without  Beveling.  —  It  is  sometimes  best  not  to 
bevel  the  edges  of  the  pieces.  This  is  true  of  thin  pieces,  where 
it  is  unnecessary.  In  the  case  of  cast  iron  and  steel,  pieces  J 
inch  thick  or  less  can  be  welded  without  making  the  V.  In 
aluminum  nothing  less  than  |  inch  thick,  and  in  brass  and 


68  PREPARATION  OF  WORK 

bronze  nothing  less  than  J  inch  thick  should  be  beveled.  These 
rules  are  only  approximate,  and  experience  will  determine  what 
should  be  done.  At  the  beginning,  it  may  be  best  to  bevel 
everything  with  the  exception  of  very  thin  pieces,  except  in 
aluminum.  Sometimes  it  is  best  to  burn  out  the  crack  without 
beveling  it.  This  is  true  of  an  irregular  piece,  not  very  heavy 
in  section,  on  which  there  are  no  finished  surfaces  that  can  be 
used  for  lining  up,  and  which  has  to  be  lined  up  true  by  the 
crack.  Burning  out  is  expensive  and  should  not  be  resorted  to 
unless  necessary.  The  metal  is  melted  with  the  torch,  and  pulled 
out  with  the  welding  stick  until  the  V  is  made,  when  the  welding 
proceeds  as  usual. 

It  requires  considerable  ingenuity  sometimes  to  prepare  a 
piece,  especially  a  heavy  one,  with  an  irregular  break,  so  that  a 
minimum  of  handling  will  result,  as  it  is  neither  desirable  nor 
comfortable  to  handle  a  heavy  red-hot  piece.  After  it  is  once 
set  up,  it  is  sometimes  dangerous  to  turn  a  heavy  piece  over, 
as  the  weld  may  break,  or  a  sudden  draft  may  crack  it  outside 
of  the  weld.  Tlje  author  has  seen  many  pieces  where  the  first 
consideration  in  preparing  has  been  ease  of  handling  while  hot, 
and  the  cheapness  of  preparing  has  been  a  minor  matter. 

Handling  Heavy  Hot  Pieces.  —  It  is  well  to  consider  the 
handling  of  heavy  hot  pieces;  they  have  frequently,  even  with 
the  best  preparation,  to  be  turned  over  or  moved  during  the 
welding.  One  must  not  be  at  all  uncertain  of  what  to  do  at 
such  times;  and  it  has  been  found  very  helpful  in  case  of  doubt 
to  put  the  cold  piece  through  the  motions  that  are  thought  to 
be  advisable  when  welding,  using  chains,  hoists,  bars,  rollers, 
etc.,  just  as  if  the  piece  were  hot.  The  temptation  to  use  the 
hands  on  the  piece  in  this  test  must  be  carefully  avoided.  This 
trial  shows  what  changes,  if  any,  should  be  made  in  the  plans, 
and  also  has  the  advantage  that  all  tools  used  may  be  laid  together 
till  needed,  and  great  loss  of  time  and  temper  avoided  by  not 
having  to  look  for  them  while  under  stress  of  work.  It  would 
appear,  therefore,  that  before  starting  a  job  careful  attention 
must  be  paid  to  planning,  as  the  preparation  has  a  very  important 
bearing  on  the  quality,  speed,  ease,  and  cost  of  the  work. 


PREPARATION  OF  WORK  69 

General  Remarks  on  Preparation  for  Welding.  —  After  the 
piece  is  beveled,  it  is  necessary  to  set  it  up  so  that  it  can  be  readily 
welded;  the  method  of  preparation  will  have  an  important 
bearing  on  this,  sometimes  deciding  the  question.  Other  things 
being  equal,  the  piece  should  be  set  with  the  weld  on  top,  so  that 
the  melted  metal  will  not  run  away.  It  is  easy  to  weld  steel  on 
the  side  or  even  on  the -bottom  of  a  piece,  and  cast  iron,  brass, 
and  bronze  may  also  be  so  handled  by  an  expert  welder;  but  it 
is  more  difficult  to  produce  as  good  a  weld,  and  some  metal  is 
lost,  making  it  a  slower  and  more  expensive  process.  Aluminum 
can  also  be  so  welded,  being  nearly  as  easy  to  handle  as  steel, 
but  it  is  seldom  necessary  to  resort  to  the  practice. 

Alignment.  —  Next  in  importance  to  a  sound  weld,  and  even 
sometimes  more  necessary,  is  the  need  of  so  welding  the  piece 
that  it  has  such  finished  surfaces  as  required  in  line.     Of  course 
it  is  not  possible  in  all  cases,  and  is  difficult  in  any  case,  to 
produce  a  perfect  condition.     In  some  cases  allowance  must  be 
made  for  machining.     No  rules  can  be  laid  down;    but  some- 
times metal  can  be  added  so  that  the  part  can  be  machined  to 
the  original  size;    sometimes  machining  may  be  done  without 
adding  metal.     Sometimes  the  metal  may  be  heated  and  sprung 
or  peened  into  place,  or  this  may  be  done  cold.     Steel  may  be 
so  treated,  either  hot  or  cold,  depending  upon  the  nature  of  the 
piece;    aluminum,  brass,  bronze,  and  malleable  castings  must 
be  peened  or  bent  cold ;  cast  iron  cannot  be  so  treated,  but  may 
sometimes  be  bent  or  straightened  by  clamping  one  end  on  the 
table,  heating  with  the  torch  to  nearly  the  melting  point,  and 
pulling  down  on  the  other  end  with  another  clamp  very  slowly. 
Warping  or  Cracking.  —  Warping  or  cracking  is  caused  by 
the  expansion  and  contraction  due  to  the  heat  of  welding    It 
is  not  possible  to  avoid  these  conditions,  and  they,  therefore, 
must  be  controlled  by  making  allowance  for  them.     The  principle 
of  control  is  best  illustrated  by  a  simple  test,  as  follows :  prepare 
two  pieces  of  cast  iron  as  shown  in  Fig.  3  and  bolt  them  tightly 
to  some  heavy  piece  of  metal ;  the  sides  of  the  holes  should  bear 
against  the  bolts  and  the  bottom  edges  of  the  V  just  touch. 
The  heavy  piece  to  which  the  smaller  pieces  are  bolted  is  kept 


70  PREPARATION   OF  WORK 

from  being  expanded  by  the  heat  from  the  torch,  by  being  put 
in  water,  or  by  some  similar  method.  Then  make  the  weld, 
using  no  more  metal  than  enough  to  fill  the  V  and  doing  the  work 
as  quickly  as  possible,  but  being  sure  to  burn  through  the  bottom 
so  that  the  weld  will  be  sound.  On  cooling  off,  the  piece  will 
invariably  break  somewhere,  and  there  will  be  a  gap  between 
the  pieces  which,  in  the  case  shown,  amounted  to  o.on  inch. 


Fig.  3.   Illustration  of  Contraction  Stresses 

If  the  piece  the  work  is  bolted  to  is  not  rigid  enough,  or  the  fit 
of  the  bolts  against  the  holes  is  not  tight,  or  if  there  is  a  trifle 
of  spring  in  some  of  the  parts,  a  light  tap  on  the  piece  may  be 
necessary  to  cause  it  to  break;  but  the  gap  will  always  be  there 
after  breakage.  If  another  test-piece  be  made,  and  the  ends 
left  free,  there  will  be  no  difficulty  in  making  a  satisfactory  weld. 
Again,  if  the  bottom  edges  of  the  V  are  butted  together,  the  ends 


PREPARATION  OF  WORK  7 1 

of  the  piece  will  rise,  which  is  only  another  manifestation  of 
shrinkage,  as  the  metal  on  top  is  hotter  than  at  the  bottom, 
and  the  bottom  edges  act  as  a  fulcrum.  The  remedy  is  to  leave 
the  pieces  slightly  apart,  or  to  clamp  or  weight  them  down. 

These  things  occur  in  every  welding  job,  whether  it  appears 
so  or  not.  Holding  the  ends  rigid  compels  the  expansion  from 
the  heat  to  go  to  the  center,  and,  when  the  piece  cools  off,  there 
is  sufficient  contraction  to  break  it.  It  is  very  easy  to  ascertain 
what  happens  in  a  simple  case  like  the  one  given,  but  the  success- 
ful application  of  the  principle  to  complicated  and  unusual 
cases  is  a  different  matter.  As  a  matter  of  fact,  making  a  sound 
weld  is  a  comparatively  easy  thing  to  learn,  and  many  learn  it; 
but  the  control  of  expansion  and  contraction  is  much  more  diffi- 
cult to  understand,  as  it  requires  a  development  of  the  imagi- 
native faculty  that  is  rarely  met  with,  and  there  are  few  who 
master  it. 

Setting-up  Work  for  Welding.  —  In  setting-up  a  piece  for 
welding,  it  should  be  done,  if  possible,  on  a  planed  surface  plate 
or  table,  using  the  finished  surfaces  of  the  piece,  if  any,  to  go  by. 
Of  course,  the  pieces  should  not  be  laid  directly  on  the  table, 
on  account  of  the  chilling  action  of  the  cold  surface,  but  parallel 
strips,  or  other  pieces  of  like  nature,  should  be  used  to  keep  the 
parts  above  the  table,  and  they  should  be  located,  if  possible, 
some  distance  from  the  weld.  If  there  are  no  finished  surfaces, 
or  if  they  cannot  be  used,  set  up  the  piece  before  making  the  V, 
using  the  crack  to  determine  the  necessary  amount  of  blocking 
to  hold  it  in  line,  and  clamping  it  so  that  it  will  not  move.  Then 
remove  the  pieces  without  disturbing  the  blocking,  V  them, 
replace  on  the  blocking,  and  reclamp.  It  is  well  in  all  cases  of 
complete  breakage  to  separate  the  parts  of  the  final  set-up  by 
just  enough  to  compensate  for  the  shrinkage  of  the  weld.  This 
is  absolutely  necessary  if  the  original  dimensions  have  to  be  main- 
tained. The  amount  of  separation  varies  with  the  piece  and 
material,  but  generally  -5%  inch  in  cast  iron  and  f  inch  in  alumi- 
num will  be  sufficient.  The  correct  amount  is  determined  by 
experience.  Sometimes  the  allowance  will  be  incorrect,  and  the 
piece  will  have  to  be  cut  and  rewelded,  changing  the  allowance. 


72  PREPARATION   OF   WORK 

In  case  great  accuracy  is  needed,  tram-marks  must  be  made  on 
the  pieces  with  a  very  fine  pointed  tram;  center-punch  marks 
are  of  little  value,  except  to  keep  the  tram-marks  from  being 
lost,  and  the  tram-marks  must  be  used. 

Frequently  it  is  necessary  to  set  up  pieces  in  the  fire,  either 
because  they  are  too  heavy  to  weld  otherwise,  or  because  .of 
expansion  or  contraction  causing  them  to  break,  if  welded  cold. 
In  such  cases,  block  them  up  as  if  on  the  table.  Care  should 
be  taken  that  the  heat  does  not  affect  the  blocking  or  pieces  so 
as  to  destroy  the  alignment,  which  should  be  again  tested  before 
welding;  be  careful  to  arrange  the  blocking  to  allow  this.  Some- 
tunes  such  pieces  may  be  clamped  to  a  heavy  block,  preferably 
of  cast  iron,  which  does  not  bend  as  readily  under  heat  as  does 
steel.  The  clamps  and  block  should  be  protected  from  the  fire, 
or  exposed  to  air  to  keep  them  cool,  if  possible.  It  is  also  pos- 
sible, at  times,  to  take  red-hot  pieces  from  the  fire  and  clamp  them 
on  the  table,  or  on  previously  prepared  blocking,  as  the  torch  will 
keep  the  parts  hot  enough  while  welding.  With  heavy  pieces 
in  large  fires  on  the  floor,  it  is  necessary  to  be  exceedingly  care- 
ful that  the  alignment  does  not  change  during  preheating.  The 
blocking  must  be  of  such  material  (preferably  cast  iron)  and  so 
arranged,  that  the  danger  of  moving  will  be  reduced  to  a  mini- 
mum. The  blocking  must  be  on  a  foundation  independent  of 
the  fire  support,  if  there  is  any  danger  of  the  latter  moving  on 
account  of  the  heat.  In  any  case,  allowance  must  be  made  for 
the  contraction  of  the  weld,  by  holding  the  crack  open  in  some 
way. 

Preheating.  —  The  general  principles  involved  in  preheating 
may  be  briefly  stated  as  follows:  Parts  to  be  welded  autoge- 
nously  are  often  preheated  by  the  use  of  a  blow-torch,  gas  fur- 
nace, charcoal  fire,  etc.  This  preheating  is  done  either  to  econo- 
mize in  gas  consumption  or  to  expand  the  metal  before  welding, 
in  order  to  compensate  for  contraction  in  cooling.  Usually  it 
is  advisable  to  preheat  comparatively  heavy,  thick  metals 
(especially  if  cast)  before  welding.  This  equalizes  the  internal 
strains,  and  very  materially  reduces  the  cost.  In  many  in- 
stances it  is  much  better  to  produce  expansion  before  welding 


PREPARATION  OF  WORK  73 

than  to  attempt  to  care  for  the  contraction  afterward.  When 
a  part  has  been  preheated,  it  is  well  to  place  sheets  of  asbestos 
over  it  to  protect  the  operator  and  prevent  heat  radiation,  the 
surface  to  be  welded  being  exposed.  Where  a  piece  of  metal 
has  been  severed  completely,  or  a  projection  has  been  broken 
off,  preheating  will  not  generally  be  necessary. 

Charcoal  for  Preheating.  —  Many  pieces  must  be  kept  hot  all 
over  while  being  welded,  and  this  cannot  be  done  with  the  torch. 
Such  parts  as  water-jacketed  cylinders,  cast-iron  heating  boiler 
sections,  aluminum  and  cast-iron  crankcases  and  transmission 
cases  for  automobiles,  and  other  large  castings,  come  under  this 
head.  Good  hardwood  charcoal  is  then  the  best  all-around 
fuel.  It  burns  without  smoke,  does  not  injure  finished  surfaces 
as  does  coal,  gives  off  no  offensive  odors,  burns  slowly  and  evenly, 
does  not  need  a  fan  blast  to  keep  it  going,  will  heat  any  piece 
red-hot,  and  is  easily  controlled.  Many  pieces  have  to  be  cooled 
off  in  the  fire  so  that  they  will  not  contract  too  fast  or  unevenly. 
Charcoal  is  also  the  best  fuel  for  this  purpose,  as  the  heat  from  it 
dies  out  slowly. 

The  best  hardwood  charcoal  is  necessary.  That  made  from 
soft  wood  breaks  up  easily,  has  little  heat,  and  clogs  up  the 
fire  so  that  it  does  not  burn  well.  It  is  advisable  to  remove 
the  dust  and  small  pieces,  by  screening  through  a  £-inch  mesh 
sieve.  For  handling  charcoal  from  the  storage  bin  to  the  fire, 
old  carbide  cans  with  the  top  cut  out  are  very  convenient  and 
save  many  steps.  It  is  well  to  store  as  little  charcoal  as  possible, 
as  it  is  easily  ignited  by  a  chance  spark;  and,  as  it  gives  no  warn- 
ing by  smoke,  it  is  liable,  if  ignited,  to  gain  considerable  headway 
before  being  observed. 

Other  Means  for  Preheating.  —  Gas  furnaces  are  very  con- 
venient for  preheating  to  reduce  the  torch  gas  expense,  but  for 
anything  else  they  are  of  little  value.  Kerosene  torches  are 
frequently  of  value  for  heavy  work  of  certain  kinds,  especially 
where  no  contraction  strains  exist.  Gasoline  torches  cannot 
be  recommended  in  a  welding  shop.  In  some  cases  ordinary 
Bunsen  burners  or  modifications  similar  to  those  used  in  gas 
stoves  may  be  used,  particularly  on  light  work.  They  are  of 


74  PREPARATION  OF  WORK 

special  value  where  many  pieces  of  one  kind  have  to  be  welded, 
because  the  burner  can  be  made  to  suit  the  job.  A  very  satis- 
factory method  of  preheating  shafts  and  other  solid  pieces  is 
by  the  use  of  a  gas  torch,  using  illuminating  or  natural  gas  and 
compressed  air  under  about  one-pound  pressure.  These  torches 
may  be  held  in  clamps,  and  mounted  on  a  flat  firebrick-covered 
table,  which  may  be  surrounded  with  firebrick,  to  keep  in  the 
heat.  It  is  necessary  to  have  a  blower  to  obtain  the  air  pressure, 
and  its  operation  is  somewhat  costly,  unless  there  is  plenty  of 
work  of  this  kind,  which  is  not  often  the  case  in  a  repair  shop. 

Object  of  Preheating.  —  There  are  two  objects  for  which  pre- 
heating is  used.  The  first,  merely  to  heat  the  piece  to  save 
time  and  gas  and  make  a  better  weld;  and  the  other,  to  take  care 
of  the  natural  contraction  of  a  welded  piece.  In  the  first  case, 
which  applies  to  plain  heavy  pieces,  it  is  only  necessary  to  put 
them  in  the  fire,  heat  them  as  rapidly  as  possible,  weld  them, 
and  allow  them  to  cool  off  slowly.  The  second  case  is  very 
different.  Such  pieces  as  gas  engine  cylinders  (which  have  two 
walls  joined  together  to  form  a  water  space),  flywheels  with 
heavy  rims  and  light  spokes,  stamping  press  and  punch-press 
frames  with  two  rigid  uprights,  automobile  crankcases  of  alu- 
minum or  cast  iron,  or  any  other  pieces  where  the  shrinkage  of 
the  weld  would  produce  a  strain,  should  be  preheated  in  part 
or  as  a  whole,  so  that  the  strains  during  the  cooling  may  be 
equalized  or  eliminated.  It  is  impossible  to  give  any  general 
directions,  but  specific  cases  are  treated  of  later. 

The  only  guide  at  the  present  time  as  to  the  amount  to  which 
a  piece  should  be  preheated  is  experience.  It  may  be  said,  how- 
ever, that  as  far  as  eliminating  strains  or  securing  a  sound  weld 
is  concerned,  taking  nothing  else  into  consideration,  the  hotter 
the  piece  is  heated  the  better.  Care  should  be  taken,  however, 
not  to  heat  a  piece  so  that  it  will  distort.  It  is  easily  possible 
to  heat  a  cast-iron  piece  so  hot  that  if  not  properly  supported 
it  will  sag  at  the  unsupported  place,  and  care  must  be  taken  to 
avoid  this.  This  property  of  cast  iron  is,  however,  of  value  at 
times  in  straightening  pieces  that  have  been  warped  by  weld- 
ing, it  being  possible  in  many  cases  to  clamp  a  piece  at  one  end 


PREPARATION   OF   WORK  75 

rigidly  on  a  true  surface  and  pull  the  other  end  down  slowly 
with  another  clamp,  while  keeping  the  weld  quite  close  to  the 
melting  point  with  the  torch. 

The  preheating  should  ordinarily  be  done  rather  slowly  so  as 
not  to  introduce  sudden  temperature  changes  and  stresses. 
Slow  heating  is  especially  to  be  advised  when  there  is  a  combina- 
tion of  thin  and  heavy  parts.  Similar  remarks  apply  to  the  cool- 
ing, which  should  be  slow  to  be  safe ;  the  cooling  may  be  retarded 
by  the  use  of  asbestos  sheeting  or  by  packing  the  object  in  heated 
ashes  or  heated  slaked  lime. 

Temporary  Furnace  for  Preheating.  —  When  it  is  possible  to 
preheat  the  entire  casting,  this  seems  to  be  the  best  way  of  taking 


I  .   I 


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EEL  BAR  -- 

I 

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Wt 

mm 

m 

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E 

-  A 

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Machinery 


Fig.  4.   Arrangement  of  Temporary  Brick  Furnace 

care  of  expansion  and  contraction.  Castings,  the  size  of  which 
makes  necessary  special  arrangements,  may  be  placed  on  a  bed 
of  firebrick  arranged  with  spaces  between  them.  A  temporary 
wall  or  furnace  is  then  built  around  the  whole,  firebrick  being 
used  for  this  also.  These  are  arranged  without  the  use  of  mortar, 
with  very  narrow  openings  between  them,  one  method  of  con- 
structing such  a  wall  being  shown  in  Fig.  4.  Flat  steel  bars 
may  be  employed  just  above  the  separated  course  of  bricks  A. 
The  top  course  may  be  held  in  place  by  a  steel  band.  The 
object  of  the  open  spaces  is  to  provide  draft.  A  small  amount 
of  lighted  charcoal  is  then  placed  around  and  under  the  casting, 
more  being  added,  from  time  to  time,  until  the  required  heat 
is  reached.  A  sheet  of  asbestos  is  used  as  a  cover.  This  cover 
should  contain  a  number  of  holes,  so  as  to  provide  an  exit  for 
the  gases. 


76 


PREPARATION   OF   WORK 


Hood  used  for  Preheating  Operations.  —  Another  method  is 
to  make  a  hood  of  a  material  that  is  a  poor  conductor  of  heat. 
Such  a  hood  is  shown  in  vertical  section  in  Fig.  5.  The  walls 
consist  of  two  sheets  of  wire  netting  with  an  intervening  space 
filled  with  asbestos.  A  hole,  the  wall  of  which  is  made  of  sheet 
iron,  is  provided  at  the  top.  Another  aperture  also  lined  with 
sheet  iron  is  provided  on  one  side  of  the  vertical  cylindrical  wall. 


WIRE  NETTING 


ASBESTOS 


CHAIN  OR  WIRE  ROPE 
SHEET  IRON 


SHIELD 


SHEET  IRON 


•W 

1    < 

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» 

B 

Sf 

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ASBESTOS-x^ 

1 

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^ASBESTOS 

Machinery 


Fig.  5.   Hood  used  for  the  Preheating  Operation 

The  bottom  of  the  hood  is  furnished  with  an  annular  base  ring 
of  sheet  iron,  the  netting  and  sheet  iron  being  joined  by  welding. 
Provision  should  be  made  for  lifting  and  lowering  the  hood,  so 
that  it  can  be  let  down  over  the  casting  which  is  to  be  preheated. 
To  make  a  tight  joint  with  the  floor,  some  loose  asbestos  may  be 
used  as  a  foundation  for  the  hood.  A  kerosene  or  other  torch 
may  now  be  inserted  through  the  aperture  in  the  side.  Some 
kind  of  shield  may  be  used  just  inside  of  the  side  opening  to  divide 
the  flame,  so  that,  as  far  as  possible,  the  casting  will  be  encircled 
by  it.  Sometimes  it  is  advisable  to  use  auxiliary  fires  on  shelves 
above  the  main  fire  at  the  bottom.  This  is  especially  to  be 
recommended  for  tall  castings,  so  that  there  will  be  no  severe 


PREPARATION   OF   WORK  77 

concentration  of  heat  at  one  point.  As  already  mentioned,  the 
heating  should  be  done  slowly,  the  fires  being  started  in  a  mod- 
erate way  and  gradually  increasing  in  intensity.  During  the 
welding,  the  hood  must  be  raised,  and  when  the  welding  is  com- 
pleted the  hood  may  again  be  lowered  into  position  in  order  to 
retard  the  cooling.  The  oil  torch  should  be  brought  into  service 
again  for  a  short  period.  It  may  then  be  shut  off  and  the  open- 
ings of  the  hood  covered.  In  this  way  slow  and  even  cooling 
is  assured.  Devices  of  this  kind  are  useful  only  for  special 
purposes,  and  are,  therefore,  limited  in  application,  although 
very  valuable  under  proper  conditions. 

In  general,  after  a  welding  operation,  the  casting  should  be 
reheated  as  soon  as  the  welding  is  completed,  and  then  covered 
with  asbestos  wool  or  scrap  asbestos.  The  casting  may  also 
be  buried  in  any  of  the  materials  ordinarily  used  for  retarding 
the  cooling  of  steel  which  is  to  be  annealed,  or  may  be  cooled  in 
the  bed  of  charcoal  in  which  it  has  been  heated. 

Preheating  Temperatures.  —  The  temperature  to  which  any 
piece  should  be  preheated  depends  upon  the  metal  of  which  it 
is  made,  its  shape,  size,  and  the  purpose  of  the  preheating.  As 
illustrations  of  the  differences  in  preheating  temperatures, 
consider,  on  the  one  hand,  a  heavy  solid  piece  of  cast  iron  the 
shape  of  which  will  not  produce  any  shrinkage  strains  when 
cooling,  and,  on  the  other  hand,  a  light  complicated  casting, 
such  as  an  automobile  cylinder.  In  the  former  case,  it  is  evident 
that  the  purpose  of  the  preheating  is  largely  to  save  gas  and 
labor,  and  that  the  preheating  can  be  carried  to  as  high  a  tem- 
perature as  a  good  red  heat,  because  there  will  be  no  danger 
from  distortion  or  cracking.  In  the  latter  instance  the  con- 
ditions are  entirely  different.  The  preheating  must  not  be 
carried  to  so  high  a  degree  as  to  warp  the  cylinder,  and  still  it 
must  be  carried  high  enough  to  permit  of  contraction  without 
cracking  when  cooling;  also,  in  this  case,  the  amount  of  gas  saved 
by  preheating  is  unimportant.  In  the  former  case  the  tem- 
perature may  be  as  high  as  1500  degrees  F.,  while  in  the  latter 
case  it  should  not  exceed  about  800  degrees  F.,  and,  in  some 
similar  cases,  where  the  shape  of  the  cylinder  is  quite  simple, 


78  PREPARATION   OF  WORK 

a  lower  temperature  is  sufficient.  The  temperatures  may  be 
taken  with  a  thermo-couple.  The  variation  of  temperature 
in  the  different  parts  of  the  casting  is  considerable,  in  some 
instances  there  being  over  200  degrees  F.  difference.  As  already 
explained,  in  preheating  a  cylinder  a  certain  procedure  should 
be  followed,  the  latter  part  of  which  is  to  turn  the  defective 
part  down,  so  that  it  may  be  warmed  up  to  a  somewhat  greater 
temperature  than  the  rest  of  the  casting.  When  turning  such 
a  casting  back,  so  as  to  reach  the  part  to  be  welded,  there  is  a 
drop  in  temperature  of,  in  some  cases,  over  100  degrees  F.  in  a 
few  seconds.  This,  of  course,  takes  place  before  the  welding 
can  be  started.  So  many  inaccurate  statements  have  been  made 


Fig.  6.   Example  of  Preheating 

as  to  the  proper  heating  temperatures  that  the  author  believes 
that  more  careful  tests  are  necessary  in  order  to  determine 
what  these  temperatures  should  be  for  different  types  of  castings. 

It  should  be  remembered,  however,  that  the  conditions  men- 
tioned control  the  situation  very  largely,  and  that,  because  one 
type  of  casting  can  be  safely  preheated  to  800  degrees  F.,  another 
casting  of  a  different  type  or  shape  may  possibly,  if  heated  to 
the  same  temperature,  cause  trouble.  Therefore,  any  figures 
given,  even  when  they  are  accurately  determined,  should  be 
followed  with  caution  and  used  with  good  judgment. 

The  only  other  metal  which,  as  a  rule,  gives  trouble  during 
preheating  and  cooling,  is  aluminum,  because  of  the  complicated 


PREPARATION  OF  WORK  79 

shapes  in  which  it  is  usually  cast,  such  as  crankcases,  transmission 
cases,  etc.,  and  from  the  fact  that  a  slight  distortion  of  such 
castings  makes  it  difficult  to  use  them  after  welding.  Aluminum 
alloys  melt  at  a  temperature  of  about  1200  degrees  F.,  but  long 
before  this  temperature  they  will  bend,  if  subjected  to  any 
strain,  and  frequently  from  their  own  weight,  which  action  is, 
of  course,  the  same  as  in  the  case  of  iron  and  steel,  although 


Fig.  7.   Hoisting  Engine  Drum  prepared  for  Welding 

cast  iron  is  not  influenced  so  much  as  the  wrought  metal.  It 
is,  therefore,  unsafe  to  preheat  to  anything  like  the  temperature 
which  is  safe  in  the  case  of  cast  iron;  about  500  degrees  F.  is 
the  safe  limit,  and,  for  all  ordinary  cases,  this  is  ample.  With 
aluminum-zinc  alloys,  where  trouble  might  occur  from  cracking 
just  after  welding,  the  piece  may  be  heated  to  about  600  degrees 
F.,  but  care  must  be  taken  to  avoid  distortion  of  the  casting 
by  its  own  weight.  It  should  also  be  remembered  that,  in  all 
cases  of  preheated  castings,  the  metal  becomes,  during  the  course 


8o 


PREPARATION  OF  WORK 


of  the  welding,  appreciably  hotter  than  the  preheating  tempera- 
ture, and  a  beginner  will  frequently  not  notice  this,  particularly 
in  the  case  of  aluminum,  until  it  is  too  late. 

Examples  of  Preheating.  —  In  Fig.  6  is  shown  an  instance  of 
the  necessity  of  proper  preheating  to  insure  sufficient  expansion 
so  that  there  will  be  no  strain  in  the  piece  after  welding.  The 
two  sides  K  are  identical  in  construction  and  the  section  below 
the  piece  broken  out  is  identical  with  it.  The  casting  is  about 

3!  feet  square,  and  the 
thickness  of  the  welds,  ex- 
cept at  the  flange,  is  about 
i  \  inch.  In  order  to  check 
the  expansion,  tram-marks 
were  made  at  A,  B,C,  and 
D,  AB  being  equal  to  CD. 
Inasmuch  as  the  casting 
was  very  rigid,  it  was  neces- 
sary to  take  special  pre- 
cautions to  avoid  strains 
in  the  welded  piece.  The 
method  followed  was  to 
heat  the  side  CD  both  top 
and  bottom  to  a  sufficient 
temperature  to  give  an 
equal  expansion  to  that  of 
the  side  AB,  which  was 
heated  only  at  the  bottom, 
in  order  to  keep  the  top  as  cool  as  possible,  forcing  the  expan- 
sion to  take  place  everywhere  except  at  the  break,  the  torch 
being  sufficient  to  counteract  the  heat  at  the  part  below  the 
break.  The  fires  were  started  slowly,  charcoal  being  used.  The 
fire  on  the  side  CD  is  longer  than  the  one  at  AB,  the  latter 
being  very  little  longer  than  the  piece  broken  out,  but  care  was 
taken  to  tram  both  sides  just  before  welding  to  be  sure  that  the 
expansion  was  the  same. 

During  the  firing,  side  CD  was  kept  covered  with  asbestos 
paper,  while  the  piece  broken  out  and  the  casting  in  the  vicinity 


Fig.  8.   Same  Drum  as  in  Fig.  7,  Welding 
Completed 


PREPARATION    OF   WORK 


8l 


were  not  so  covered.  Care  was  taken,  however,  to  prevent 
sparks  from  rising  from  the  fire  by  covering  the  space  between  the 
bricks  and  AB.  The  illustration  shows  the  bricks  X  laid  on 
their  side  to  permit  a  good  view  of  the  breaks,  but  they  were  later 
placed  on  edge  in  order  to  confine  the  heat.  The  fire,  however, 
was  not  allowed  to  reach  the  break,  but  was  kept  about  3  inches 
above  the  bottom  section.  A  large  tip  was  used  to  make  the 
welds,  as  the  casting  was  comparatively  cold.  Weld  F  was  made 

first,  allowed  to  cool  to  the      t 

temperature  of  the  casting, 

the     tram-marks    checked 

again,    and    then  weld   H 

made.     Both    welds   were 

burnt  entirely  through  from 

the  top,  and  each  one  was 

finished    underneath    after 

it  was  made,  taking  down 

enough  of  the  outside  bricks 

to  reach  it,  and  covering 

over  the  fire  to  hold  the 

heat  in  the  bottom  section. 

After  welding,    this  cover 

was    removed,    the   bricks 

replaced,  and   the   casting 

allowed   to    cool    down  in 

the  fire.     It  was  found  that 

before   welding  at  H,  the 

crack  was  open  about  -%-%  inch,  which  was  sufficient  under  the 

conditions  to  take  care  of  the  contraction.     It  is  necessary  in 

this  and  similar  cases  to  make  the  weld  as  quickly  as  possible, 

so  that  the  heat  conditions  at  all  points  will  remain  as  nearly 

constant  as  possible. 

Preheating  a  Rope  Drum.  —  Fig.  7  shows  the  method  of 
preparing,  blocking  up,  and  preheating  the  rope  drum  from  a 
hoisting  engine.  Both  ends  were  cracked  in  the  same  way, 
although  the  upper  one  in  the  illustration  was  not  cracked  so 
badly.  It  was  impossible  to  prepare  the  drum  from  the  other 


Fig.  9.   Drum  shown  in  Fig.  7  finished 


82  PREPARATION  OF  WORK 

side,  which  would  have  been  desirable  on  account  of  the  greater 
ease  of  doing  the  work,  as  it  could  have  been  done  under  a  drill 
press.  The  crack  extended  through  at  the  root  of  the  friction 
block  cavity,  making  it  impossible  to  prepare  by  any  other 
method  except  that  used.  An  electric  drill  was  used  and  the 
necessary  material  chipped  away  as  shown,  the  same  procedure 
being  followed  on  both  ends  to  produce  the  Vs.  As  the  casting 
was  quite  heavy,  it  was  necessary  to  block  it  up  inside  of  the 
crack,  because  if  it  had  been  blocked  up  under  the  outside,  it 
would  probably  have  been  distorted  when  it  became  red  hot. 
Fig.  7  also  shows  the  pieces  of  sheet  iron  practically  surrounding 
the  casting,  and  the  charcoal  in  place  ready  to  ignite.  Of  course, 
pieces  of  sheet  iron  entirely  surrounded  the  flange  during  the 
preheating,  welding,  and  cooling  off.  Care  was  taken  to  melt 
through  the  bottom  of  the  crack  to  insure  a  sound  weld.  Fig.  8 
shows  the  piece  after  welding.  There  was  no  necessity  for  any 
finishing  except  just  sufficient  grinding  with  a  flexible  shaft 
emery  wheel  to  remove  the  principal  roughness,  so  that  the  rope 
would  not  chafe.  The  finished  appearance  is  shown  in  Fig.  9. 


CHAPTER  III 
MATERIALS   AND    FLUXES   USED    FOR   WELDING 

IN  nearly  every  case  of  oxy-acetylene  welding  it  is  necessary 
to  use  additional  material  to  fill  up  the  V  left  by  the  preparation 
of  the  piece.  The  material  to  use  for  this  purpose  depends  partly 
upon  the  metal  in  the  piece  and  partly  on  the  result  desired; 
in  almost  all  cases  this  additional  metal  is  furnished  in  the  form 
of  wire  or  rods  from  -jV  to  f  inch  in  diameter.  Special  cases  may 
require  larger  or  smaller  sizes,  but  it  has  been  found  that  the 
range  given  is  ample  to  cover  the  ordinary  run  of  repair  work. 

Welding-rod  for  Cast  Iron.  —  For  welding  cast  iron,  the 
material  used  is  cast-iron  rods  from  yV  to  f  inch  in  diameter, 
the  small  rods  being  used  for  small  work  and  small  tips,  while 
the  heavier  rods  are  for  the  larger  work  and  heavy  tips.  When 
the  pieces  of  the  welding-rod  become  too  short  to  hold  comfort- 
ably, they  may  be  welded  together,  and  so  used  up.  The  cast 
iron  in  these  rods  should  be  of  first-class  quality,  high  in  silicon 
and  low  in  manganese  and  sulphur,  so  that  it  may  be  easily 
melted,  reducing  the  gas  consumption  and,  consequently,  the 
expense,  and  producing  a  soft  weld.  These  rods  are  at  present 
a  specialty;  it  is  a  serious  mistake  to  use  cheap  welding-rods 
of  improper  composition,  as  the  gas  consumption  is  much  higher, 
and  the  work  much  slower  and  of  poor  quality,  resulting  in 
increased  cost  and  unsatisfactory  results. 

When  oxy-acetylene  welding  first  became  a  commercial 
process,  great  difficulty  was  experienced  in  welding  cast  iron, 
on  account  of  the  hardness  of  the  welds,  which  prevented  their 
being  machined  in  any  way,  except  by  grinding.  This  was  due 
to  the  use  of  ordinary  cast  iron  for  welding  rods.  Such  cast 
iron  has  comparatively  little  silicon  and  considerable  manganese 
and  sulphur  in  it.  Silicon  promotes  the  formation  of  graphite 
in  iron,  which  makes  it  soft,  while  manganese  and  sulphur  have 

83 


84  MATERIALS  AND  FLUXES 

just  the  opposite  effect;  thus  it  will  be  seen  that  the  use  of  ordi- 
nary cast  iron  tends  to  produce  white  iron  or  chilled  iron  con- 
taining no  graphitic  carbon,  and  which  is  intensely  hard.  The 
increase  of  silicon  and  the  decrease  of  manganese  in  welding- 
rods  overcomes  these  objections  and  makes  possible  the  pro- 
duction of  a  soft  weld.  The  manufacturing  of  such  welding 
sticks  cannot  be  carried  out  in  an  ordinary  foundry,  as  the  iron 
is  not  suitable.  Therefore,  it  must  be  left  to  those  who  make  a 
specialty  of  this  work.  There  are  several  foundries  in  the  United 
States  that  do  nothing  else,  and  the  material  can  be  obtained 
from  them,  or  from  the  manufacturers  of  welding  apparatus. 

Welding-wire  for  Steel.  —  In  welding  steal,  nothing  but  the 
best  and  most  suitable  wire  should  be  used.  Wire  purchased 
at  an  ordinary  hardware  store  is  of  no  value,  as  it  is  of  improper 
composition,  being  frequently  high  in  sulphur  and  phosphorus, 
and,  as  a  rule,  also  too  high  in  carbon;  hence,  it  will  not  give  good 
results.  It  is  generally  claimed  that  Swedish  (often  called  Norway) 
iron  wire  is  the  best  for  this  purpose  and  that  the  imported 
wire  is  better  than  the  domestic.  This  is  true  for  ordinary  steel, 
although  it  does  not  make  a  homogeneous  weld.  A  highly 
polished  section  through  a  weld  made  with  Swedish  iron  wire 
shows  a  very  marked  difference  between  the  original  and  added 
materials.  Etching  such  a  piece  for  microscopic  examinations 
shows  the  difference  still  more  clearly,  the  etching  action  being 
much  slower  on  the  added  material.  It  is,  however,  somewhat 
of  a  question  whether  material  with  a  small  percentage  of  carbon, 
say,  o.i  per  cent,  or,  perhaps,  as  low  as  0.05  per  cent,  would  not 
give  just  as  good  results,  provided  the  impurities,  such  as  sulphur 
and  phosphorus,  were  kept  to  as  low  a  point  as  is  the  case  in  Swed- 
ish iron.  There  are  other  matters  in  connection  with  this  subject 
that  have  never  been  investigated,  as  far  as  the  author  knows, 
and  inasmuch  as  their  investigation  requires  great  accuracy, 
and  considerable  time  and  expense,  the  lack  of  information  is 
not  to  be  wondered  at.  It  is  a  fact,  however,  that  the  use  of 
Swedish  iron  or  any  pure  iron  wire  gives  good  results,  and, 
until  the  matter  is  more  carefully  investigated,  one  is  safe  in 
using  that  material. 


MATERIALS   AND   FLUXES  85 

There  are  advertised  a  number  of  other  materials,  such  as 
nickel  steel,  vanadium  steel,  etc.,  with  which  the  author  has 
had  but  little  experience.  On  theoretical  grounds,  however, 
the  use  of  these  materials  is  questionable.  Vanadium  is  never 
added  to  steel  in  any  appreciable  amount.  Whether  such  steel 
would  retain  its  properties  after  being  heated  to  the  welding 
temperature  is  still  another  question,  and  if  a  weld  can  be  pro- 
duced by  the  use  of  Swedish  iron,  which  is  strong  and  ductile 
enough,  the  use  of  alloy  steels  appears  to  be  unnecessary.  The 
use  of  alloy  steels  for  welding  has  never  been  carefully  investi- 
gated, and,  as  in  other  matters  of  this  kind,  innovations  should 
be  considered  with  caution. 

Alloy  Steel  Welds.  —  It  should  be  remembered  that  any 
weld  is  a  casting,  no  matter  what  the  metal  may  be,  and  that  it 
is  impossible,  in  most  cases,  to  produce  as  satisfactory  a  condition 
in  the  weld  as  in  the  original  metal,  even  with  the  best  welding 
material  and  fluxes,  unless  the  weld  can  be  given  the  same  roll- 
ing or  forging  treatment  as  that  to  which  the  original  metal  was 
subjected.  In  the  case  of  alloy  steels,  which  are  largely  used 
in  automobiles,  proper  heat-treatment  must  be  given  in  addition 
to  forging  of  the  steel.  These  results  are  not  often  possible  to 
obtain,  because  the  piece  cannot  generally  be  forged;  nor  does 
it  contain  the  necessary  elements  for  successful  heat-treatment, 
since  the  joint  is  not  a  homogeneous  weld.  In  addition,  no 
welding  shop  has  facilities  for  conducting  such  heat-treatments. 
Therefore,  in  such  cases,  a  welded  piece  will  not  give  satis- 
factory results.  This  is  not  the  fault  of  the  welder,  of  the  ma- 
terial, or  of  the  flux,  but  is  an  inherent  limitation  of  the  process. 
It  is,  therefore,  advisable  to  avoid  welding  such  steel  pieces, 
except  in  case  of  emergency  or  for  temporary  purposes  only. 

Welding-wire  for  Spring  Steel.  —  It  is  sometimes  advisable 
or  necessary  to  weld  broken  leaves  in  automobile  springs,  and 
while  it  appears  a  doubtful  performance,  as  far  as  strength  is 
concerned,  the  author  has  never  known  one  welded  in  his  shops 
to  break.  The  proper  material  to  use  for  this  is  old  bed  springs, 
which  can  usually  be  found  around  an  ordinary  scrap  yard. 
Ordinary  welding-wire  is  not  satisfactory.  Care  must  be  taken 


86  MATERIALS  AND  FLUXES 

in  using  this  material  not  to  burn  it.  A  fairly  large  tip  should 
be  employed  and  the  work  done  rapidly. 

Welding  Material  for  Steel  Castings.  —  The  welding  of  steel 
castings  is  generally  possible  and  gives  good  results.  There 
are  some  kinds,  however,  that  are  difficult  to  weld,  and  others 
can  only  be  welded  with  cast  iron.  Evidently,  if  strength  is 
a  consideration,  cast  iron  must  not  be  used.  Usually  ordinary 
welding-wire  is  suitable,  but  it  is  well  to  keep  the  pieces  that  are 
cut  out  during  the  preparation,  so  that,  in  case  it  is  found  diffi- 
cult to  weld  with  ordinary  steel,  the  pieces  themselves  may  be 
used  as  a  filler,  at  least  as  far  as  they  will  go.  Sometimes  it  is 
possible  to  cut  off  surplus  metal  from  other  parts  of  the  casting 
and  use  it. 

Welding  Material  for  Tool  Steel. —  The  welding  of  tool 
steel  is  generally  unsatisfactory,  particularly  where  the  material 
is  to  be  used  for  heavy  cutting.  It  is  not  possible  to  avoid 
entirely  the  burning  of  the  metal.  Borax  or  other  suitable  flux 
should  be  used  as  a  coating  for  the  steel,  to  help  keep  the  air 
from  it.  The  use  of  spring  steel  wire  for  filling,  and  of  a  rather 
large  tip,  with  the  quickest  possible  speed  for  doing  the  work, 
will  give  as  good  results  as  can  be  obtained.  It  is  a  material 
that  is  very  seldom  handled  in  repair  shops. 

Welding-rods  for  Copper  and  Copper  Alloys.  —  For  welding 
copper,  copper  wire  or  rod  having  a  small  percentage  of  phos- 
phorus is  advisable.  The  phosphorus  eliminates  the  oxygen 
which  would  otherwise  be  absorbed  by  the  copper,  and  which 
would  make  the  weld  porous.  The  amount  of  phosphorus  in 
the  welding-rod  should  be  such  that  none  of  it  is  left  in  the  weld, 
or  a  brittle  constituent  is  likely  to  be  present. 

The  alloys  of  copper  include  the  various  brasses  and  bronzes, 
which  are  exceedingly  numerous  and  of  a  great  variety  of  com- 
positions. A  brass  is  an  alloy  of  copper  and  zinc.  A  bronze 
is  an  alloy  of  copper  and  tin.  These  alloys  may  have  added  to 
them  lead,  antimony,  iron,  manganese,  nickel,  etc.,  in  smaller 
percentages  than  the  main  constituents.  Inasmuch  as  it  is 
impracticable  in  ordinary  repair  work  to  determine  the  per- 
centage of  the  elements  in  copper  alloys,  it  is  manifestly  impos- 


MATERIALS   AND   FLUXES  87 

sible  to  make  a  truly  homogeneous  weld,  i.e.  one  containing  the 
same  elements  as  the  piece  to  be  welded.  Of  course,  where  the 
process  is  used  in  manufacturing  and  the  composition  of  the  alloy 
is  known,  some  experimenting  will  enable  one  to  determine 
the  most  suitable  mixture  to  use  for  welding-rods;  but  in  repair 
work  it  is  necessary  to  find  some  one  or  two  alloys  which  will 
apply  to  all  of  the  metals  that  are  likely  to  be  met  with. 

This  is  well  taken  care  of  by  the  manufacturers  of  welding 
apparatus  and  welding  material,  and  suitable  rods  for  general 
brass  and  bronze  welding  can  best  be  obtained  from  them.  / 

The    best    all-around    welding  material    is    ma^igajie^-^rariz^ 

although  Tobin  bronze  may  also  be  used  with  good  results. 
The  so-called  manganese-bronze  is  really  a  manganese-brass, 
because  the  two  principal  ingredients  are  copper  and  zinc,  the 
percentage  of  tin  being  quite  small.  Rolled  manganese-bronze 
rod  or  wire  is  quite  fluid  and  makes  a  very  good  weld.  Tobin 
bronze  is  somewhat  more  fluid,  and  while,  in  many  cases,  it  works 
well,  yet  if  the  melting  point  of  the  piece  that  is  being  welded 
is  high,  due  to  the  presence  of  a  considerable  percentage  of  copper, 
it  may  be  difficult  to  get  the  piece  to  melt  at  the  same  time  as 
the  welding-rod;  manganese-bronze,  not  melting  at  quite  so  low 
a  temperature,  is,  therefore,  more  satisfactory,  as  a  general  rule. 
Tobin  bronze  is  really  a  Tobin  brass,  as  it  consists  mostly  of 
copper  and  zinc. 

It  should  be  understood  that  the  percentage  of  the  various 
elements  in  both  manganese-bronze  and  Tobin  bronze  may 
vary  considerably,  so  that  they  are  not  alloys  of  constant  com- 
position, the  difference  depending  upon  the  ideas  of  the  manu- 
facturers; but  both  contain  some  iron,  which  appears  to  give 
greatly  increased  strength  and  makes  the  essential  difference 
between  the  properties  of  these  metals  and  ordinary  brass. 
As  all  brasses  contain  zinc,  which  readily  volatilizes  under  the 
heat  of  the  torch,  the  advisability  of  having  a  considerable 
percentage  of  zinc  in  the  welding-rod  is  apparent. 

Manganese-bronze  can  be  used  in  the  form  of  J-inch  sticks 
12  inches  long  and  can  be  made  by  any  good  brass  foundry. 
For  sheet  brass,  rolled  manganese-bronze  or  Tobin  bronze 


88  MATERIALS   AND   FLUXES 

rods  of  the  proper  size,  TV  or  J  inch,  are  most  satisfactory,  as  they 
make  a  little  smoother  weld  and  are  more  fluid.  This  fluidity 
is  sometimes  a  disadvantage,  particularly  in  welding  on  curved 
surfaces,  and  it  is  well  to  have  the  various  kinds  of  welding- 
rods  on  hand,  using  the  one  that  suits  the  case  best.  As  far  as 
strength  is  concerned,  there  appears  to  be  no  practical  difference. 

Welding  Material  for  Aluminum.  —  For  cast  aluminum,  an 
alloy  of  93  per  cent  of  aluminum  and  7  per  cent  of  copper,  which 
is  the  standard  No.  12  mixture,  gives  satisfactory  results  and  can 
be  cast  by  any  good  aluminum  foundry  in  sticks  J  inch  in  diam- 
eter and  12  inches  long.  It  is  convenient  for  small  work  to  have 
sticks  TV  inch  in  diameter  and  sometimes  for  large  work  f  inch 
is  better,  but  it  is  seldom  that  either  of  the  two  latter  sizes  is 
required.  Of  course,  where  large  numbers  of  pieces  of  the  same 
composition  are  to  be  welded,  as  in  manufacturing  work,  the 
proper  alloy,  which  will  be  nearly  the  same  as  the  castings, 
should  be  used.  But  as  it  is  not  possible  to  know  the  composi- 
tion of  all  alloys  handled  by  a  repair  shop,  one  mixture,  such  as 
given  above,  has  to  be  adopted  as  a  compromise.  For  sheet 
aluminum,  strips  of  the  same  metal  are  generally  most  satisfac- 
tory, although  aluminum  wire  is  frequently  employed.  Cast 
aluminum  sticks  cannot  be  used. 

Material  for  Welding  Malleable  Iron.  —  In  the  case  of  thin 
sections  of  malleable  iron  which  are  of  the  "  white-heart "  variety, 
it  is  possible  to  weld  them  with  regular  steel  welding-wire,  and 
this  should  be  attempted  in  such  cases  before  anything  else  is 
done.  In  "  black-heart "  castings,  the  use  of  steel  wire  will  simply 
result  in  the  metal  sticking  to  the  wire  and  pulling  away  from  the 
casting,  the  same  as  when  it  is  attempted  to  use  welding  wire 
on  cast  iron.  In  addition  to  this,  blow-holes  apparently  form  in 
the  piece.  In  cases  where  strength  is  not  necessary,  such  as 
in  filling  holes  or  covering  over  defects,  cast  iron  is  the  best 
material  to  use.  It  amalgamates  quickly  with  the  malleable 
iron  and  makes  a  good  smooth  job,  but  the  chances  are  in  favor 
of  hard  spots  being  produced,  from  the  melted  malleable  iron 
becoming  white  or  chilled  iron  on  solidifying.  For  the  majority 
of  work,  manganese-bronze  is  the  best  to  use,  and  that  coming  in 


MATERIALS   AND   FLUXES  89 

rolled  rods  is  most  satisfactory.  Properly  used,  a  first-class 
job  can  be  done,  and,  as  the  bronze  is  stronger  than  the  malleable 
iron,  "the  weld,  if  properly  made,  will  give  no  trouble.  Malle- 
able iron  should  not  be  brought  quite  to  the  melting  point, 
and,  after  a  little  experience,  this  can  be  determined  with  great 
accuracy.  If  it  is  hotter  than  this,  it  is  detrimental  to  the 
strength  of  the  casting.  There  are  no  two  pieces  of  malleable 
iron  alike;  thus  it  is  impossible  to  predict  what  the  result  will 
be  before  the  welding  is  begun. 

Fluxes  used  for  Oxy-acetylene  Welding.  —  Those  who  are 
familiar  with  oxy-acetylene  welding  are  aware  that  fluxes, 
scaling  powders,  etc.,  are  used;  but  it  is  not  generally  known 
why  the  use  of  these  fluxes  is  necessary.  They  are  sometimes 
used  in  the  shape  of  powders  into  which  the  welding-rod  is 
dipped,  thereby  transferring  the  flux  to  the  weld;  or  they  may  be 
incorporated  in  the  welding-rod  itself.  Also  a  special  welding- 
rod  containing  certain  elements  may  be  used  in  connection  with 
a  powdered  flux.  Inasmuch  as  each  metal  has  different  char- 
acteristics and  requires  different  treatment  during  the  welding 
process,  the  nature  of  the  flux  varies  with  the  metal.  Therefore, 
it  will  be  well  to  consider  each  metal  separately,  first  explaining 
the  nature  of  the  difficulties  encountered  and  then  describing 
the  remedies  which  are  applied,  including,  as  far  as  possible,  the 
materials  used  for  making  the  fluxes.  It  should  be  stated  here 
that  the  manufacture  of  satisfactory  fluxes  requires  considerable 
chemical  knowledge  and,  in  the  majority  of  cases,  should  not 
be  undertaken  by  a  welding  shop,  because  of  the  difficulty  of 
obtaining  the  proper  amount  of  the  necessary  elements  and  mixing 
them  properly,  and  because  it  is  cheaper,  as  a  general  rule,  to 
buy  the  fluxes  from  the  manufacturers  than  to  attempt  to  make 
them. 

Flux  for  Cast  Iron.  —  Melted  cast  iron  has  a  great  affinity 
for  oxygen,  which  combines  with  it  to  form  an  oxide  of  iron  or 
slag.  This  affinity  which  molten  iron  possesses  for  oxygen  is 
well  illustrated  by  the  amount  of  slag  produced  during  the  cutting 
of  steel,  this  slag  being  oxide  of  iron.  In  the  case  of  cast  iron 
the  oxide  is  lighter  than  the  melted  metal  and  does  not  melt 


QO  MATERIALS   AND   FLUXES 

at  quite  so  low  a  temperature.  Being  lighter,  it  rises  to  the 
surface,  which  makes  it  easier  to  dispose  of.  Many  kinds  of 
fluxes  for  cast  iron  are  furnished  by  the  manufacturers  of  welding 
apparatus,  or  by  manufacturing  chemists,  which  vary  consid- 
erably in  composition,  but  which,  as  far  as  the  author's  experience 
goes,  differ  but  little  in  efficiency.  The  principle  of  all  of  them  is 
to  provide  some  chemical  which,  at  the  high  temperature  in- 
volved, will  break  up  the  oxide  into  its  component  parts. 

For  cast  iron,  a  mixture  of  equal  parts  of  carbonate  of  soda 
and  bicarbonate  of  soda  makes  a  very  satisfactory  flux.  Ordi- 
nary washing  soda  is  the  name  commonly  given  to  a  somewhat 
impure  carbonate  of  soda.  Bicarbonate  of  soda  is  ordinary 
baking  soda.  The  carbonates  can  be  obtained  in  a  chemically 
pure  condition  from  the  manufacturers  of  chemicals,  but  the 
author  finds  no  particular  advantage  in  their  use.  A  good  way 
to  prepare  the  flux  is  to  grind  the  washing  and  baking  sodas 
together  in  an  ordinary  meat  grinder,  passing  the  material 
through  the  hopper  two  or  three  times  in  order  to  secure  a  thor- 
ough mixture.  Somewhat  more  of  this  mixture  will  be  used 
in  welding  than  would  be  the  case  if  one  of  the  higher  priced 
fluxes  was  used;  but  as  both  ingredients  are  obtainable  at  any 
grocery  store  at  a  trifling  cost,  the  difference  in  cost  more  than 
offsets  the  difference  in  the  amount  used.  The  action  of  the 
carbonates  is  to  combine  with  the  oxygen  in  the  slag,  releasing 
the  iron  and  allowing  the  oxygen  to  pass  off  in  the  form  of  carbon 
monoxide  or  carbon  dioxide. 

It  will  be  noticed,  in  the  use  of  a  cast-iron  flux,  that  as  soon 
as  a  small  portion  of  it  is  put  on  the  melted  iron,  the  surface  of 
the  metal  becomes  clear  and  mirrorlike,  and  that,  under  such 
conditions,  the  union  of  the  metal  in  the  piece  and  the  metal 
from  the  welding  stick  is  easily  made.  The  necessity  of  using 
a  flux  for  cast  iron  may  not  be  thoroughly  appreciated,  but  if 
an  attempt  is  made  to  weld  cast  iron  without  it,  difficulties  will 
at  once  be  experienced. 

Steel  and  Wrought-iron  Flux.  —  In  welding  these  metals, 
a  flux  is  not  ordinarily  used,  although  there  is  a  certain  amount 
of  oxide  formed  which  may  be  removed  b}'  the  use  of  a  cast-iron 


MATERIALS   AND   FLUXES  91 

flux.  The  melting  points  of  both  soft  steel  and  wrought  iron 
are  higher  than  the  melting  point  of  the  oxide,  and,  while  the 
oxide  is  lighter  than  the  melted  metal,  there  is  more  or  less 
tendency  for  it  to  sink  into  the  body  of  the  weld.  The  judicious 
use  of  a  small  amount  of  flux  will  help  this  difficulty.  In  welding 
steel,  however,  the  principal  thing  to  guard  against  is  burning 
the  work,  which  no  flux  will  overcome,  and  which  ruins  the  weld 
beyond  repair.  While  it  is  not  necessary  to  use  a  flux  in  making 
ordinary  steel  welds,  it  is  absolutely  necessary  to  use  the  proper 
kind  of  welding-rod  or  wire.  The  higher  the  jjercentage  of  carbon 
in  the  steel,  the  greater  is  the  danger  of  burning.  The  author 
does  not  believe  it  possible  to  burn  wrought  iron,  which  is  simply 
steel  with  an  exceedingly  low  percentage  of  carbon,  the  only 
difference  between  the  two  metals  being  due  to  the  method  of 
manufacture,  which,  in  the  case  of  wrought  iron,  naturally 
produces  a  metal  with  less  carbon.  Inasmuch  as  the  welding- 
wire  is  generally  of  considerably  smaller  section  than  the  weld, 
there  is  a  greater  liability  of  burning  the  wire  than  the  weld. 
The  proper  manipulation  of  the  torch  will  help  to  overcome 
trouble  from  this  source,  but  the  necessity  of  having  a  welding- 
rod  that  is  not  easily  burnt  is  obvious,  and,  therefore,  iron  wire 
is  used. 

Copper  Welds.  —  There  is  no  necessity  for  using  a  flux  for 
welding  copper,  if  the  surfaces  are  clean  and  if  the  proper  welding- 
rod  is  used.  Ordinary  copper  is  quite  free  from  impurities, 
because  traces  of  such  impurities  make  it  impossible  to  use  the 
copper.  This  metal,  however,  has  several  peculiar  properties. 
When  melted,  it  has  a  strong  affinity  for  gases,  such  as  hydrogen 
and  carbon  monoxide.  Oxygen  is  also  absorbed  by  the  melted 
metal,  producing  copper  oxide  which  forms  a  true  alloy  with 
the  copper,  making  it  brittle  and  worthless.  When  the  metal 
solidifies,  these  occluded  gases  are  given  out,  leaving  the  metal 
a  mass  of  blow-holes.  It  is,  therefore,  necessary  to  provide 
something  which  has  a  greater  affinity  for  oxygen  than  the  copper. 
This  is  done  by  the  use  of  phosphorus,  which,  instead  of  being 
used  as  a  flux,  is  incorporated  in  the  welding-rod.  Only  a  small 
percentage  of  phosphorus  is  required,  as  none  should  remain  in 


92  MATERIALS  AND   FLUXES 

the  weld  after  it  is  made,  although  small  traces  of  phosphorus 
in  copper  have  no  bad  effect  on  its  physical  properties.  It  is 
evident  that  the  production  of  such  welding-rods  or  wire  is  a 
matter  which  should  be  left  in  the  hands  of  competent  manu- 
facturers. This  special  copper-welding  material  can  also  be 
obtained  from  apparatus  manufacturers. 

Fluxes  for  Copper  Alloys.  —  Theoretically,  the  fluxes  for 
a  copper  alloy  should  depend  upon  the  composition  of  the  alloy, 
but,  while  there  are  some  objections  to  it,  for  all  practical  pur- 
poses ordinary  borax  gives  very  good  results.  To  prepare  the 
borax  for  use,  it  should  be  melted  and  then  allowed  to  cool,  after 
which  it  is  powdered,  because  in  its  original  condition  the  borax 
does  not  lie  quietly  in  the  weld,  but  foams  up  and  a  great  deal  of 
it  is  wasted.  It  is  the  author's  experience  that  greater  success 
is  obtained  by  using  a  satisfactory  welding-rod  for  copper  alloys 
than  by  varying  the  fluxes.  When  the  composition  of  the  piece 
being  welded  is  unknown,  the  use  of  one  flux  may  be  satisfac- 
tory while  another  one  is  not.  Borax  seems  to  be  the  best  all- 
around  substitute.  In  welding  brasses  and  bronzes,  care  should 
be  taken  not  to  heat  the  piece  too  hot.  If  carefully  observed, 
it  will  be  noticed  that  at  a  certain  temperature  the  prepared 
surfaces  will  show  little  globules  rising  from  them.  The  degree 
of  temperature  just  a  trifle  above  this  point  is  the  temperature 
at  which  the  metal  from  the  welding- rod  should  be  added.  It  will 
be  found  that  if  this  is  done  a  satisfactory  weld  will  be  made, 
provided  the  surfaces  are  clean  and  a  small  amount  of  borax  is 
used  as  a  flux. 

Flux  for  Aluminum.  —  At  high  temperatures  aluminum  has 
a  strong  affinity  for  oxygen.  At  ordinary  temperatures  pure 
aluminum  is  but  little  affected,  but  all  ordinary  aluminum 
pieces,  which  are  generally  alloys  of  aluminum  and  copper  or 
of  aluminum  and  zinc,  tarnish  more  rapidly.  The  tarnish  is 
due  to  the  formation  of  a  thin  film  of  oxide  of  aluminum.  Un- 
like iron  or  steel,  where  the  oxidization  or  rusting  goes  on  indefi- 
nitely, the  thin  film  of  oxide  on  the  surface  of  aluminum  protects 
the  metal  from  further  attack  at  ordinary  temperatures.  How- 
ever, when  aluminum  is  melted,  it  oxidizes  freely,  and  as  the 


MATERIALS   AND   FLUXES  93 

/ 

oxide  or  slag  is  heavier  than  the  melted  metal  and  melts  at  a 
very  much  higher  temperature,  the  tendency  is  for  it  to  become 
mixed  with  the  molten  metal  and  weaken  the  weld.  This  action 
of  the  oxide  makes  it  very  troublesome  for  a  beginner  to  weld 
aluminum. 

The  chemical  inertia  of  the  oxide  makes  it  exceedingly  difficult 
to  decompose  with  a  flux,  even  at  the  temperature  of  melted 
aluminum.  Fluxes  for  this  purpose,  therefore,  have  to  be  very 
strong  and  chemically  active,  and  one  difficulty  with  those  which 
the  author  has  used  is  the  after-action  on  the  aluminum,  a  large 
number  of  pieces  having  been  observed  in  which  the  metal  for 
some  distance  around  the  weld  had  been  seriously  injured  by 
this  action,  although  it  took  some  time  for  the  damage  to  develop. 
In  some  cases  instructions  are  issued  that,  after  the  welding 
is  done,  the  piece  must  be  thoroughly  brushed  off  with  boiling 
water  to  remove  the  remnants  of  the  flux  and  prevent  this  action. 
It  is  also  the  author's  experience  that,  after  a  weld  has  been 
made  with  a  flux,  should  a  crack  develop  in  it  or  near  it,  such  a 
crack  cannot  be  welded  without  considerable  difficulty,  if  it 
can  be  welded  at  all,  unless  the  surface  is  thoroughly  cleaned 
and  the  metal  in  the  old  weld  has  been  removed.  Also,  while 
it  is  theoretically  advisable  to  use  a  flux,  and  while  in  the  case 
of  sheet  aluminum  it  is  necessary  to  do  so,  there  are  other  reasons 
in  the  case  of  repairs  to  such  castings  as  automobile  crankcases, 
transmission  cases,  etc.,  why  the  use  of  a  flux  is  difficult.  The 
principal  ones  are  the  condition  of  the  surface  before  welding, 
and  the  fact  that  it  is  not  desirable,  in  the  case  of  thin  sections 
of  aluminum,  to  prepare  the  piece  by  beveling  it,  as  is  done  in 
the  case  of  iron  and  steel.  There  is  considerable  shrinkage  in 
an  aluminum  weld,  and  it  is  advisable  to  resist  this  as  much  as 
possible  by  leaving  the  full  thickness  of  the  section,  the  thin 
edge  of  a  prepared  piece  having  less  area  and,  therefore,  offering 
less  resistance.  Of  course,  this  will  not  stop  shrinkage  entirely, 
but  it  helps  to  do  so. 

Cleaning  of  Aluminum  Work.  —  Before  any  flux  can  be  used, 
the  surface  must  be  entirely  cleaned.  Frequently,  it  is  not  pos- 
sible to  do  this,  although  the  use  of  strong  acid  and  alkali,  such  as 


94  MATERIALS   AND   FLUXES 

hydrochloric  acid  and  caustic  soda  (applied  to  the  work  sepa- 
rately), followed  by  a  thorough  washing  and  brushing  in  water 
afterward,  will  remove  the  grease  and  dirt  from  the  exposed 
surfaces.  It  will  not,  however,  remove  the  oxide  nor,  as  a  gen- 
eral rule,  will  it  remove  the  grease  and  dirt  from  the  crack  or 
break,  because  they  are  more  or  less  absorbed  by  the  aluminum, 
which  is  porous.  This  absorption  extends  in  some  cases  for  quite 
a  distance  from  the  break,  and,  unless  such  metal  is  entirely 
cut  out,  the  use  of  a  flux  will  be  found  unsatisfactory.  Of  course, 
in  some  cases  it  is  possible  to  spring  a  piece  to  allow  for  contrac- 
tion, but  in  other  cases  this  is  not  feasible  and  other  remedies 
must  be  resorted  to.  The  narrower  the  weld,  the  less  the  con- 
Table  I.  Composition  of  Flux  for  Welding  Aluminum 


Ingredients 

Per  Cent 

Lithium  chloride  

1C 

Potassium  chloride  

AC 

Sodium  chloride  

?o 

Potassium  fluoride  

7 

Potassium  bisulphate  

traction  and  distortion  of  the  piece,  and  so  the  less  metal  removed 
the  better. 

Composition  of  Aluminum  Fluxes.  —  A  number  of  fluxes  are 
sold  by  the  apparatus  manufacturers  and  the  chemical  companies, 
which  vary  in  composition,  and  these  firms  should  be  consulted 
as  to  the  best  flux  to  use,  the  conditions  under  which  it  is  to  be 
applied  being  thoroughly  explained.  Sheet  aluminum  work  is 
generally  a  manufacturing  proposition,  sheet  aluminum  being 
used  largely  for  automobile  and  carriage  bodies  and  similar 
purposes.  A  flux  is  necessary  for  the  proper  performance  of 
the  work,  but  as  the  surfaces  are  clean  the  same  objections  to  a 
flux  do  not  exist  as  in  the  case  of  broken  parts,  and  a  proper 
flux  will  make  the  weld  just  as  tough  and  capable  of  standing  as 
much  work  as  the  original  sheet.  A  flux  which  was  devised  in 
France  in  the  laboratory  of  the  Autogenous  Welding  Association 
has  the  composition  given  in  Table  I.  A  very  small  amount 
of  this  flux  is  all  that  is  necessary,  but  it  should  be  remembered 


MATERIALS   AND   FLUXES 


95 


that  it  is  necessary  to  wash  the  flux  off  carefully,  as  previously 
explained.  This  flux  gives  a  bright  red  color  to  the  flame  when 
it  is  applied,  which  is  characteristic  of  lithium  salts.  The  author 
has  used  this  flux  and  finds  that,  as  would  be  suspected  by  one 
familiar  with  the  chemical  properties  of  its  ingredients,  it  is 
exceedingly  active.  It  is,  however,  open  to  the  objections  men- 
tioned above.  The  composition  of  a  number  of  other  fluxes 
are  given  in  Table  II.  Most  of  these  are  patented  in  Europe, 

Table  II.  Fluxes  for  Welding  Aluminum 


g-sg 

.2  'CO 

m 

Potassium 
Chloride, 
Per  Cent 

! 

Sodium 
Fluoride, 
Per  Cent 

Potassium 
Fluoride, 
Per  Cent 

Sodium 
Bisulphate 
Per  Cent 

Potassium 
Bisulphate 
Per  Cent 

Sodium 
Sulphate, 
Per  Cent 

Potassium 
Sulphate, 
Per  Cent 

Cryolite 
(Aluminum 
sodium  Fluo 
ide),PerCe 

30.0 

45-0 

15.0 

7 

3 

33-4 

33-3 

33-3 

12.5 

62.7 

20.8 

4 

16.0 

79.0 

5 

17.0 

83.0 

6-5 

56.0 

23-5 

4 

IO 

in  the  country  of  their  origin.  As  will  be  seen,  the  composition 
is  a  mixture  of  alkaline  chlorides  in  various  proportions.  The 
melting  point  of  the  flux  must  be  somewhat  below  that  of  the 
metal  so  that  the  former  will  melt  and  flux  away  the  oxide  just 
before  the  metal  begins  to  flow.  In  actual  use  the  flux  powder 
is  moistened  down  with  alcohol.  Otherwise  it  will  be  scattered 
by  the  draft  from  the  blowpipe;  in  its  dry  form  too  the  powder 
is  very  hygroscopic  and  liable  to  deteriorate,  due  to  absorption 
of  moisture.  Another  method  employs  the  flux  in  the  form  of 
a  core  to  the  feeding  stick  which  is  made  hollow  for  the  purpose. 
This,  as  a  rule,  can  only  be  used  as  supplementary  to  the  flux 
pasted  on  the  joint. 

Welding  Aluminum  without  a  Flux.  —  In  most  cases,  a  weld 
can  be  made  without  the  use  of  a  flux  in  the  time  taken  to  pre- 
pare the  piece  so  that  a  flux  can  be  used.  Therefore,  for  prac- 
tical purposes,  the  use  of  a  flux  in  other  than  special  cases  is 
believed  by  the  author  to  be  inadvisable,  and  a  resort  to  the 
puddling  of  the  weld  with  a  rod  made  of  soft  steel  about  TF  inch 


96  MATERIALS   AND   FLUXES 

in  diameter  and  bent  to  the  desired  shape  appears  to  be  the  best 
way  out  of  the  difficulty.  It  is  true  that  more  or  less  oxide  is 
included  in  welds  thus  made,  but  the  fact  remains  that  they  are 
strong  enough  for  service  and  tests  show  that  they  are  generally 
stronger  than  the  surrounding  metal.  This  being  the  case, 
it  is  evidently  a  question  whether  or  not  it  is  advisable  to  resort 
to  the  use  of  a  flux.  The  puddling  must  be  thoroughly  done 
and  care  must  be  taken  to  keep  the  metal  melted  while  it  is 


Fig.  1.  Polished  Aluminum  Surfaces.  A  shows  a  High-grade  Casting 
before  welding;  B,  C,  and  D  show  the  Surface  of  another  Piece 
of  Aluminum  — B  before  being  welded,  C  after  being  welded  by  the 
Puddling  Process,  and  D  after  being  welded  with  a  Flux 

going  on;  but  if  the  proper  precautions  are  observed  there  will 
be  no  serious  defects  visible  in  the  weld  through  an  ordinary 
magnifying  glass,  and  the  work  will  last  as  long  as  the  original 
part. 

Acquiring  the  necessary  skill  to  enable  one  to  make  a  satisfac- 
tory weld  in  this  way  takes  time,  and  some  men  never  become 
good  aluminum  welders.  Close  observation  and  the  frequent 
breaking  of  test-pieces  will  show  whether  the  necessary  skill  is 


MATERIALS   AND   FLUXES  97 

/"" 

being  acquired,  and  what  is  necessary  to  do  in  order  to  overcome 
any  difficulties  that  may  arise.  There  are  two  other  points  to 
be  considered  in  connection  with  the  use  of  an  aluminum  flux. 
First,  there  is  no  aluminum  casting  made  that  is  not  more  or 
less  porous,  due  to  the  presence  of  oxide  in  it.  This  being  the  case, 
the  author  does  not  see  any  use  in  trying  to  make  the  weld  any 
better  than  the  casting.  Second,  even  by  the  use  of  a  flux,  it 
is  not  possible  to  make  a  perfectly  sound  weld,  although,  under 
the  best  conditions,  it  is  somewhat  freer  from  porosity  than  one 


Fig.  2.    Section  of  a  Boss  built  up  in  Aluminum  by  Puddling 

made  without  a  flux.  Therefore,  the  question  of  the  use  of  a 
flux  with  aluminum  castings  is  a  practical  one  rather  than  theo- 
retical, and  in  the  author's  mind  the  arguments  against  the  use 
of  a  flux  carry  more  weight  than  those  in  favor  of  it. 

Examples  of  Welds  made  with  and  without  Flux.  —  In  sup- 
port of  the  author's  contention  that  a  flux  is  not  necessary  in  order 
to  secure  a  satisfactory  weld  in  aluminum,  attention  is  called  to 
the  accompanying  illustrations.  In  Fig.  i  it  will  be  noticed 
that  the  defects  in  the  original  pieces  of  metal  A  and  B  are  as 
bad  or  worse  than  in  the  puddled  weld  C,  while  even  the  weld  Z>, 


98  MATERIALS  AND  FLUXES 

in  which  a  flux  was  used,  is  not  by  any  means  perfect.  Also, 
after  comparing  Figs.  2  and  3,  it  will  again  be  noticed  that  while 
the  flux  does  remove  the  defects  to  some  extent,  the  weld  so  pro- 
duced is  not  perfect  by  any  means.  It  is  almost  too  much  to 
expect  that  in  the  operation  of  welding  a  flux  can  be  made  to 
penetrate  to  all  parts  of  the  weld  and  to  come  in  contact  with 
every  particle  of  oxide,  no  matter  how  carefully  the  work  is  done. 
It  should  be  stated  that  piece  A,  Fig.  i,  was  taken  from  the  trans- 


Fig.  3.   Section  of  a  Boss  built  up  in  Aluminum  by  Welding 
with  a  Flux 

mission  case  of  one  of  the  best  automobiles  manufactured  in  the 
United  States,  and  was  selected  with  a  view  of  obtaining  as  good 
a  piece  of  aluminum  as  possible.  The  quality  of  the  metal 
was  so  good,  and  it  welded  so  nicely,  that  the  man  doing  the  work 
commented  on  it  by  saying,  "This  is  aluminum"  his  meaning 
being  obvious. 

Aluminum  Alloys.  —  The  principal  alloys  used  in  the  United 
States  for  aluminum  castings  that  the  ordinary  repair  welding 
shop  meets  with  are  composed  of  about  93  per  cent  of  aluminum 
and  7  per  cent  of  copper ;  while  in  England  and  on  the  Continent 
the  general  alloy  appears  to  be  about  90  per  cent  of  aluminum 


MATERIALS  AND   FLUXES  99 

and  10  per  cent  of  zinc.  In  both  cases,  other  elements  are  present 
in  small  quantities.  The  zinc  alloy  is  somewhat  stronger  at 
ordinary  temperatures  than  the  copper  alloy,  but  has  the  peculiar 
disadvantage  of  being  very  brittle  at  a  temperature  just  below 
the  solidification  point.  This  makes  it  difficult  to  cast,  par- 
ticularly if  the  pieces  are  of  a  complicated  shape;  but  while  a 
welder  may  encounter  some  of  these  zinc  alloys,  particularly 
in  parts  cast  a  number  of  years  ago,  at  the  present  tune  he  will 
find  but  few  of  them.  This  is  considerably  to  his  advantage, 
because  it  is  sometimes  very  difficult  .to  weld  an  aluminum-zinc 
alloy  on  account  of  the  tendency  of  the  shrinkage  strains  to  crack 
the  metal.  The  author  has  frequently  found  it  necessary  in 
such  cases  to  purposely  cut  the  casting  at  a  point  where  it  can  be 
sprung  to  compensate  for  the  shrinkage,  but  in  several  cases  has 
found  it  impossible,  even  by  doing  this,  to  avoid  cracking.  A 
zinc  alloy  can  generally  be  readily  detected  by  the  condensation 
of  the  white  fumes  of  oxide  of  zinc  on  the  colder  parts  of  the 
casting.  In  such  cases  thoroughly  preheating  the  whole  piece 
to  the  highest  safe  temperature  undoubtedly  helps  to  reduce  the 
shrinkage  strains. 

Constitution  of  Malleable  Iron.  —  This  metal  is  a  very  pe- 
culiar one,  and,  on  account  of  its  method  of  manufacture,  but 
little  is  generally  known  of  its  peculiarities  and  characteristics. 
Gray  cast  iron  contains  carbon  in  two  states;  in  one  case,  it  is 
combined  chemically  with  some  of  the  iron  in  the  form  of  carbide 
of  iron,  a  hard,  white,  brittle,  and  weak  substance.  In  the  other 
form,  the  carbon  exists  as  free  graphite,  which  is  in  the  form  of 
thin  plates  or  flakes  which  break  up  the  continuity  of  the  iron, 
and  its  presence  largely  accounts  for  the  comparatively  low 
strength  of  cast  iron.  White  iron  or  chilled  iron  has  no  free 
carbon  in  it,  all  of  the  carbon  existing  in  the  combined  state 
as  carbide  of  iron.  Malleable  iron  is  manufactured  by  packing 
the  castings,  which  are  made  of  white  cast  iron,  in  boxes  filled 
with  some  pulverized  material  such  as  iron  ore,  lime,  or  sand, 
and  subjecting  them  to  a  high  temperature  for  several  days, 
so  that  some  of  the  combined  carbon  is  partly  removed  by  being 
oxidized;  but  it  is  mostly  changed  into  a  third  condition,  which 


100  MATERIALS  AND   FLUXES 

is  called  "temper  carbon."  This  latter  change  cannot  take  place 
in  the  presence  of  any  appreciable  amount  of  graphite,  which 
is  the  reason  for  using  white  iron  in  the  process.  This  temper 
carbon  is  chemically  and  physically  the  same  as  the  graphite 
before  mentioned,  but  it  is  present  in  the  form  of  small  rounded 
masses,  which  do  not  detract  from  the  strength  of  the  material, 
as  do  the  plates  of  graphite  in  gray  cast  iron.  It  is  not  necessary 
to  go  further  into  the  metallurgy  of  malleable  iron,  except  to 
say  that  the  quality  of  a  malleable-iron  casting  depends  upon 
the  material  in  which  it  is  packed  during  the  annealing  process, 
on  the  time  to  which  it  is  subjected  to  the  heat,  on  the  tempera- 
ture, and  on  the  original  quality  of  the  material  from  which  it 
is  made.  If  the  casting  is  small,  if  it  is  packed  in  such  a  material 
as  iron  oxide,  and  if  it  is  subjected  for  a  long  enough  time  to  a 
sufficiently  high  temperature,  a  large  percentage  of  the  carbon 
may  be  eliminated,  resulting  in  the  formation  of  a  crude  steel. 
Such  castings  can  be  welded  with  ordinary  steel  welding-wire 
and  very  good  results  obtained.  In  a  thick  casting,  however, 
particularly  if  it  is  not  packed  in  iron  oxide  or  some  similar 
material,  the  action  is  different,  and  the  resulting  metal  is  not 
a  crude  steel  but  a  form  of  cast  iron,  except  on  the  outside, 
where  there  will  be  a  thin  layer  of  the  steel  formation.  A  welder 
who  observes  closely  will  notice  that  such  a  casting  acts  pecu- 
liarly. The  outside  skin  is  hard  to  melt  and  acts  as  steel  does 
under  the  torch;  while  the  center  part  acts  more  like  cast  iron, 
becomes  full  of  blow-holes,  and  cannot  be  welded  with  steel, 
but  will  weld  readily  with  cast  iron,  as  in  fact  the  whole  section 
will  do.  At  times,  such  a  weld  is  strong  enough,  but  it  has 
only  the  strength  of  the  cast  iron  and  will  tend  to  be  extremely 
hard. 

A  little  consideration  will  show  why  this  is  naturally  the  case. 
The  original  metal  of  which  the  casting  was  made  was  cast  iron 
of  such  a  composition  that  it  chills,  even  when  poured  in  sand 
without  a  chill  plate,  so  that  the  melting  of  the  malleable  iron 
tends  to  return  it  to  its  original  condition  of  chilled  or  white 
cast  iron,  which  is  very  hard  and  brittle.  This  accounts  for  the 
hard  spots  and  brittleness  of  a  malleable-iron  weld  made  with 


MATERIALS   AND   FLUXES  IOI 

malleable-iron  welding-rods.  Of  course,  it  is  possible  to  elimi- 
nate these  difficulties  by  again  putting  the  piece  through  the 
malleabilizing  process,  but  this  is  not  possible  in  ordinary  repair 
work,  so  that  other  means  must  be  resorted  to  for  joining  the 
broken  parts.  It  is  impossible,  therefore,  to  produce  a  truly 
homogeneous  weld  in  malleable  iron  without  putting  it  through 
the  malleabilizing  process.  Experience  has  shown  that  the  most 
satisfactory  and  practical  way  of  joining  broken  malleable-iron 
parts  is,  as  already  mentioned,  by  using  manganese-bronze  of 
the  proper  composition.  Care  should  be  taken  not  to  heat 
the  malleable  iron  too  hot,  and  it  must  not  be  melted,  but  only 
brought  to  the  temperature  at  which  the  bronze  will  alloy  with 
it,  and  the  weld  should  be  somewhat  reinforced.  Borax  used 
as  a  flux  gives  very  good  results. 

General  Remarks  on  Fluxes.  —  It  should  be  remembered 
in  all  discussions  of  fluxes  that  the  flux  used  depends  upon  the 
kind  of  welding  material  used  and  vice  versa,  as  well  as  on  the 
material  which  is  being  welded;  so  that  no  general  rules  can  be 
laid  down  governing  all  cases.  More  or  less  experimenting  has 
to  be  done  by  every  welding  shop,  particularly  by  beginners, 
because  they  are  not  able  to  reproduce  at  will  the  same  condi- 
tions in  the  use  of  the  torch;  and  the  variations  existing  from 
this  cause  frequently  overshadow  or  entirely  obliterate  the  re- 
sults obtained  by  the  use  of  certain  fluxes  and  welding  materials. 
The  preceding  outline,  however,  is  the  result  of  the  author's 
experience  during  the  past  six  years  in  welding  over  22,000 
pieces  of  all  kinds  and  qualities  of  metal.  That  there  will  be 
changes  in  the  practice  of  oxy-acetylene  welding  is  undoubted. 
That  new  methods  will  be  discovered  is  not  questioned,  as  it  is 
not  to  be  expected  that  any  process  of  so  recent  an  origin  as  oxy- 
acetylene  welding  is  fully  developed.  However,  the  author 
believes  that  the  composition  of  fluxes  and  welding  materials 
should  be  determined  in  laboratories  equipped  for  accurate 
work,  and  that  rough  experimenting  without  facilities  for  prop- 
erly checking  and  determining  the  results  is  a  detriment  rather 
than  a  benefit  to  the  art.  He  therefore  recommends  that,  except 
where  it  is  specifically  stated  above,  fluxes  and  welding  materials 


102  MATERIALS  AND   FLUXES 

be  either  purchased  from  the  manufacturers  or  from  those  fur- 
nishing the  apparatus,  and  that  time  and  money  be  not  wasted 
in. making  experiments  that  have  probably  been  made  before 
by  others  better  fitted  to  interpret  the  results. 


CHAPTER  IV 
MAKING    OXY-ACETYLENE    WELDS 

A  BRIEF  review  of  the  practice  of  making  oxy-acetylene 
welds  may  be  of  value  at  this  point.  The  details  are  referred 
to  in  other  chapters,  but  the  general  principles  should  be  thor- 
oughly understood.  To  become  proficient  in  the  art  of  autoge- 
nous welding  requires  experience  and  practice,  but  a  knowledge 
of  some  of  the  fundamental  principles  will  enable  the  operator 
to  make  more  rapid  progress.  It  is  advisable  to  begin  by  welding 
cast  iron,  and  then  thin  strips  of  iron  or  steel  not  over  f  inch  in 
thickness.  Such  thin  strips  can  be  welded  without  the  addition 
of  a  filling-in  material;  the  torch  should  be  given  a  rotary  motion 
accompanied  by  a  slight  upward  and  forward  movement  with 
each  rotation.  This  movement  tends  to  blend  the  metal  and 
reduces  the  liability  of  overheating.  If  comparatively  thick 
materials  are  to  be  welded,  the  edges  should  be  beveled  (by 
chipping,  or  in  any  other  convenient  way),  as  already  mentioned. 
The  beveled  surfaces  are  then  heated  by  a  circular  movement 
of  the  flame,  care  being  taken  to  melt  them  to  a  soft,  plastic 
state  without  burning  the  metal.  Wherever  fusion  occurs, 
new  metal  should  be  added  from  a  welding-rod,  the  composition 
of  which  is  suitable  for  the  work  in  hand.  In  continuing  the  heat- 
ing operation,  the  flame  should  be  swung  around  in  rather  small 
circles  and  be  advanced  slowly  to  distribute  the  heat  and  pre- 
vent burning.  The  surface  should  be  thoroughly  fused  before 
adding  metal  from  the  welding  stick,  and  the  latter  should  be 
held  close  to,  or  in  contact  with,  the  surface.  The  heat  is  then 
radiated  from  the  welding-rod  to  the  work,  whereas,  if  the  metal 
were  allowed  to  drop  through  the  flame,  it  might  be  burned  to 
an  injurious  extent.  When  the  weld  is  completed,  it  is  advisable 
to  pass  the  torch  over  it,  so  that  all  parts  will  cool  from  a  nearly 
uniform  temperature. 

103 


104  MAKING   OXY-ACETYLENE   WELDS 

When  welding  parts  together,  it  is  important  not  to  heat 
one  more  than  the  others,  because  the  hottest  piece  will  expand 
most  and  the  weld  may  crack  in  cooling  as  the  result  of  uneven 
contraction.  When  making  heavy  welds,  the  parts  should  be 
brought  to  a  red  heat  for  a  distance  of  about  three  times  the 
thickness  on  each  side  of  the  weld,  for  thicknesses  up  to  one  inch, 
the  distance  being  increased  somewhat  for  heavier  parts. 

General  Rules  for  Welding.  —  There  are  a  number  of  points 
to  be  considered  in  oxy-acetylene  welding,  which  apply  equally 
to  the  welding  of  all  metals.  These  will  now  be  considered,  and 
in  subsequent  chapters  the  special  points  applying  individually 
to  each  metal  will  receive  attention.  Some  of  the  instructions 
may  seem  unnecessarily  minute,  and  even  superfluous,  but  the 
author  has  obtained  the  best  results  by  adhering  closely  to  the 
rules  laid  down. 

1.  Follow   strictly   and   without   deviation   the   instructions 
given  by  the  manufacturers  of  the  apparatus  used,  in  every 
respect.     Reputable  manufacturers,  the  only  ones  whose  appa- 
ratus should  be  purchased,  are  not  only  willing,  but  anxious, 
to  assist  when  difficulties  are  encountered.     These  manufacturers 
have  spent  thousands  of  dollars  to  find  out  how  to  handle  their 
apparatus,  and  it  is  to  be  assumed  that  they  know  the  best  way 
and  instruct  accordingly. 

2.  Remember  that  a  welding  torch  is  an  instrument  of  pre- 
cision, and  handle  it  as  such.     Throwing  it  down  on  a  table, 
dropping  it  on  the  floor,  or  other  misuse,  will  result  in  more  or 
less  injury  to  the  welds  made.     If  the  torch  tip  becomes  hot, 
do  not  plunge  the  whole  head  in  water.     Cool  off  the  tip  first. 
When  it  is  thoroughly  cool,  the  head  may  be  cooled  off.     Lack 
of  attention  to  this  point  in  certain  types  of  torches  will  damage 
the  end  of  the  tip  in  the  head,  and  may  cause  injury  to  the 
threads  in  the  head,  when  the  tip  is  removed. 

3.  Keep  the  torch  in  first-class  condition,  free  from  leaks,  and 
with  clean  tips.     See  that  the  gages  register  properly  at  all  times, 
and  that  the  reducing  valves  act  promptly.     Good  results  cannot 
be  obtained  with  defective  apparatus.     See  that  all  joints  are 
tight,  so  that  neither  acetylene  nor  oxygen  may  be  wasted.     An 


MAKING   OXY-ACETYLENE   WELDS  105 

oxygen  leak  may  not  seem  very  dangerous,  but  it  may  result  in 
a  rapid  burning  of  the  welder's  clothes  or  cause  some  wooden 
article  to  burn  where  a  spark  falls  on  it,  when  otherwise  no 
damage  would  result.  An  acetylene  leak  is  dangerous.  If  it 
were  generally  appreciated  that  a  quart  can  filled  with  an  ex- 
plosive mixture  of  acetylene  and  air  has  enough  potential  energy 
to  kill  a  person  near  by,  no  acetylene  leaks  would  be  permitted. 
Be  particularly  careful  to  see  that  no  leaks  exist  in  the  hose  or 
torch.  The  hose  on  the  floor  is  liable  to  have  pieces  of  metal 
dropped  on  it  which  damage  it,  and  even  with  the  best  of  care 
it  will  in  the  course  of  time  wear  out,  the  inner  lining  becoming 
porous  and  allowing  the  escape  of  the  gases.  Hose  in  this  con- 
dition cannot  be  repaired;  it  is  dangerous  and  should  be  replaced 
at  once.  Leaks  around  the  torch  are  liable  to  burn  the  welder 
and  cause  explosions,  and  should  not  be  tolerated. 

4.  Adhere  strictly  to  the  pressures  specified  by  the  manu- 
facturer for  the  different  sizes  of  tips.     Do  not  attempt  to  force 
the  tip  by  increasing  the  gas  pressure  to  obtain  a  larger  flame, 
but  use  a  larger  size  of  tip.     The  excess  of  oxygen  caused  by 
the  forcing  of  the  tip  will  result  in  decreasing  the  strength  of 
steel  welds  and  will  damage  other  welds  seriously.     This  is  a 
point  which  is  generally  overlooked,  but  which  is  exceedingly 
important.     Use  a  tip  large  enough  to  do  the  work  easily,  but 
under  no  circumstances  use  too  large  a  one,  as  damage  to  the 
weld  will  probably  result. 

5.  Unless  otherwise  specified,  always  use   a   neutral   flame. 
The  flame  of  a  torch  may  contain  an  excess  of  acetylene  or  an 
excess  of  oxygen,  or  it  may  be  strictly  neutral.     It  is  not  to  be 
understood  by  the  expression  " neutral"  that  one  torch  may  not 
consume  more  oxygen  than  another,  even  when  the  flames  appear 
neutral  in  both  cases.     The  neutrality  of  the  flame  refers  to  the 
small  welding  flame  only,  and  simply  indicates  that  to  the  eye 
the  flame  has  just  sufficient  oxygen  to  burn  the  acetylene  com- 
pletely and  no  more.     If  care  is  not  used,  a  considerable  amount 
of  oxygen,  over  and  above  this  requirement,  may  escape  through 
the  torch  tip  and  damage  the  weld. 

6.  Always  light  the  acetylene  first  and  turn  it  off  last.     In 


106  MAKING  OXY-ACETYLENE   WELDS 

some  types  of  torches,  this  may  avoid  an  explosion  or  "back- 
fire," which,  while  it  may  cause  no  damage,  is  to  be  avoided 
whenever  possible.  Back-fire,  as  it  is  commonly  called,  is  really 
a  burning  of  the  acetylene  inside  of  the  torch.  This  is  accom- 
panied by  a  deposit  of  soot  which  may  collect  in  the  small  pas- 
sages and  prevent  the  torch  from  working  satisfactorily.  If 
this  is  the  case,  the  passages  will  have  to  be  cleaned  out,  although 
sometimes  the  deposit  will  burn  out  after  a  short  period  of  use. 
The  temporary  reduction  in  the  size  of  the  welding  flame,  how- 
ever, tends  to  make  a  bad  mixture,  with  resulting  damage  to 


Fig.  1.   Neutral  Flame  enlarged  about  Three  Times 

the  weld.  Never  use  any  oil  or  grease  around  a  torch  nor  around 
anything  exposed  to  the  action  of  oxygen.  Fires  may  result 
from  this,  as  the  oil  is  rapidly  oxidized  with  a  considerable  in- 
crease of  temperature. 

7.  It  may  seem  superfluous  to  mention  that  an  acetylene 
leak,  particularly  in  a  generator,  should  not  be  stopped  by  at- 
tempting to  weld  it,  or  by  using  any  heat  at  all;  but  there  has 
been  at  least  one  case  of  this  kind  which  resulted  in  the  explosion 
of  the  generator  and  the  instant  death  of  the  man  who  attempted 
to  weld  it. 

8.  In  case  repairs  are  needed  on  the  torch,  it  is  best  to  send  it 


MAKING  OXY- ACETYLENE  WELDS  107 

to  the  manufacturers.  A  mechanic  familiar  with  the  construc- 
tion can,  of  course,  make  repairs,  but  the  relation  of  the  sizes 
of  the  passages  to  each  other  must  be  maintained  for  efficient 
work,  and  the  manufacturer  can  do  this  best. 

9.  Never  use  copper  tubing  for  acetylene  piping.  It  is  easily 
attacked  by  acetylene,  at  least  under  certain  conditions,  and 
an  explosive  compound  is  created  which  detonates  at  the  least 
shock. 

The  Oxy-acetylene  Flame.  —  Fig.  i  shows  a  photograph 
of  the  neutral  flame  as  it  appears  to  the  eye,  but  magnified  three 


Fig.  2.   Neutral  Flame  photographed  through  a  Light  Filter 

times.  The  length  is  about  three  times  the  diameter  of  the 
largest  part;  the  small,  intensely  white  flame  A  is  sharp  in  out- 
line, and  is  symmetrical  and  smooth.  A  jagged  or  irregular 
flame  indicates  that  the  hole  in  the  end  of  the  tip  is  not  true, 
or  is  rough;  it  is  necessary  occasionally  to  run  a  drill  of  the 
exact  size  carefully  into  this  end  and  to  clean  it  out  and  true 
it  up.  The  use  of  a  soft  wire  has  been  advised  for  this  purpose; 
but  it  is  not  possible  to  obtain  good  results  in  this  way.  The 
thinner  flame  B,  as  it  appears  in  the  illustration,  is  due  to  the 
burning  of  the  hydrogen  left  when  the  acetylene  is  broken  up 
into  its  constituents,  carbon  and  hydrogen.  The  fact  that  the 


108  MAKING   OXY-ACETYLENE   WELDS 

photograph  was  given  a  one-minute  exposure  with  a  very  rapid 
plate  shows  that  the  conditions  were  not  very  different  during 
that  time,  because  of  the  sharp  outlines  of  both  flames.  It  might 
be  stated  that  this  stability  of  the  flame  is  characteristic  of  the 
torch  used  to  produce  the  photograph. 

Fig.  2  shows  the  correct  shape  of  the  neutral  flame.  This 
photograph  was  taken  with  quite  a  long  exposure  through  a 
light  filter,  the  conditions  not  being  changed  in  any  way  from 
those  under  which  Fig.  i  was  taken.  It  will  be  noticed  that, 
while  the  flame  is  of  the  same  length,  the  width  has  been  reduced ; 


Fig.  3.  Appearance  of  Flame  with  an  Excess  of  Acetylene 

the  hydrogen  flame  has  practically  disappeared.  It  will  be  also 
noticed  that  there  is  a  considerable  halo  on  both  sides  of  the 
flame,  which  the  author  believes  is  caused  by  a  small  amount  of 
acetylene  which  escapes  without  combining  directly  with  the 
oxygen,  and  which  is  probably  burnt  by  oxygen  from  the  sur- 
rounding air.  It  will  be  noticed  that  there  is  none  of  this  halo 
at  the  end  of  the  flame.  This,  however,  does  not  now  appear 
to  be  of  serious  importance  from  the  practical  side  of  welding. 

In  Fig.  3  it  will  be  noticed  that  the  neutral  flame  has  entirely 
disappeared  and  in  its  place  is  a  longer  white  flame,  character- 


MAKING   OXY-ACETYLENE   WELDS 


109 


istic  of  an  excess  of  acetylene.  When  the  acetylene  is  reduced, 
or  the  oxygen  increased,  this  flame  decreases  in  size  and  becomes 
sharply  defined,  this  being  the  neutral  flame.  Upon  a  further 
increase  of  oxygen  with  no  change  in  the  acetylene,  this  sharply 
defined  neutral  flame  becomes  somewhat  shorter  and  takes  on 
a  violet  tint  which  indicates  a  surplus  of  oxygen  in  the  flame 
itself.  If  the  increase  of  oxygen  continues,  the  flame  will  be 
blown  out.  This  excess-of-oxygen  flame  is  shown  in  Fig.  4, 
and  it  will  be  noticed  that  it  is  shorter  than  the  neutral  flame 
and  also  smaller  in  diameter,  and  that  it  has  a  bulbous  enlarge- 


Fig.  4.   Appearance  of  Flame  with  an  Excess  of  Oxygen 

ment  at  the  end,  while  the  neutral  flame,  as  it  appears  to  the  eye, 
is  more  elliptical.  It  will  also  be  noticed  that  the  outline  of 
this  flame  is  sharper.  The  hydrogen  flame  has  a  peculiar  shape 
at  the  top.  The  cause  of  this  is  not  at  present  known,  but  it 
is  probably  due  to  the  peculiar  shape  of  the  small  flame,  which 
is  not  symmetrical.  It  is  believed  that  this  is  the  first  time  that 
photographs  of  the  various  flames  have  been  published,  and  their 
appearance  indicates  the  necessity  of  further  study  of  them. 
For  the  present  purpose,  it  is  enough  to  show  them  as  they 
actually  appear. 


110  MAKING   OXY-ACETYLENE   WELDS 

The  Neutral  Flame.  —  All  instructions  as  to  the  operation 
of  welding  torches  or  blowpipes  explain  how  a  neutral  flame  is 
produced  and  state  that,  when  the  oxygen  pressure  is  turned  on 
sufficiently  to  just  destroy  the  double  cone  produced  by  a  defi- 
ciency of  oxygen,  the  flame  is  neutral.  It  is  evident  that  with  a 
given  acetylene  pressure  in  a  given  torch  only  one  oxygen  pres- 
sure will  produce  this  result,  and  that  if  the  acetylene  pressure 
be  varied,  the  oxygen  pressure  must  also  be  varied,  so  that  with 
any  torch  a  large  number  of  neutral  flames  is  possible.  The 
author  does  not  know  of  any  tests  having  been  made  to  prove 
that  the  flame  is  really  neutral,  that  is,  that  there  is  no  excess 
of  oxygen  or  acetylene  in  or  surrounding  the  flame.  Neither 
does  he  know  of  any  accurate  tests  made  as  to  the  relative 
amounts  of  oxygen  and  acetylene  consumed  by  any  type  or 
design  of  torch,  and  believes  that  such  tests  would  be  quite 
difficult  to  make.  Theoretically,  one  volume  of  oxygen  is  neces- 
sary in  a  torch  to  burn  one  volume  of  acetylene,  both  being  pure. 
Inasmuch  as  neither  oxygen  nor  acetylene  is  ever  absolutely  pure, 
and  as  it  is  impossible  to  produce  in  any  torch  theoretically  per- 
fect conditions,  any  claim  that  torches  can  be  so  made  as  to  con- 
sume equal  volumes  of  oxygen  and  acetylene  appears  to  be 
unfounded.  It  would  also  appear  that  the  question  of  the 
real  neutrality  of  the  flame  is  one  that  is  still  open  for  serious 
investigation.  In  spite  of  these  difficulties,  it  has  been  amply 
proved  in  practice  that  a  torch  of  good  design,  used  as  instructed 
by  the  manufacturers,  and  with  a  neutral  flame  produced  with 
the  pressures  for  which  the  torch  is  designed,  will  give  sat- 
isfactory results,  and  these  matters  are  referred  to  only  for  the 
purpose  of  making  clear  some  things  that  are  generally  much 
misunderstood. 


CHAPTER  V 
OXY-ACETYLENE    WELDING    OF    CAST    IRON 

CAST  iron  is  the  easiest  metal  to  weld,  and,  therefore,  should 
be  the  first  one  tried  by  the  beginner.  It  is  best  to  begin  with 
small  pieces,  say,  f  by  2  inches  in  section.  Bevel  both  sides 
of  the  two  pieces  so  that  the  included  angle  is  about  90  degrees 
(see  Fig.  2,  Chapter  II)  and  grind  off  the  sand,  scale,  and  dirt 
for  about  |  inch  away  from  the  V.  Set  the  ends  about  -^V  inch 
apart,  and  somewhat  above  the  surface  of  the  table,  say,  on  two 
V-blocks  of  the  same  thickness. 

Making  the  Weld.  —  Use  the  size  of  tip  recommended  by  the 
manufacturer,  adjust  the  flame  to  neutral,  and  bring  both  edges 
to  a  bright  red;  then  melt  down  the  bottom  of  the  V,  applying 
a  little  flux  or  scaling  powder  with  the  heated  end  of  the  filling 
rod.  Do  not  add  any  metal  from  the  filling  rod  until  the  bottom 
of  the  V  is  filled  from  the  sides.  Be  sure  that  the  metal  runs 
together  freely.  When  ready  to  add  metal,  put  the  end  of  the 
filling  rod  in  the  melted  metal  of  the  weld  and  play  the  flame 
on  both  the  rod  and  the  weld  so  that  the  metal  runs  together. 
As  often  as  is  necessary,  dip  the  rod  in  the  scaling  powder  and 
proceed  with  the  filling  in.  Be  careful  not  to  add  too  much  at 
one  time,  using  just  enough  to  make  the  metal  run  freely.  The 
weld  should  be  made  in  steps.  If  too  much  metal  is  added  in 
one  place,  it  is  likely  to  run  over  into  the  bottom  of  the  V,  and, 
unless  the  welder  is  experienced  and  careful,  will  cause  a  cold 
shut  which  makes  a  defective  weld.  As  the  filling  progresses, 
be  sure  that  the  metal  is  welded  at  both  sides.  Most  welders 
are  right-handed  and  the  tendency  is  to  get  the  left  side  of  the 
weld  well  made,  while  the  right  side  is  likely  to  be  "cold-shut" 
on  account  of  sufficient  heat  not  being  applied  at  that  point. 
The  "feel"  of  the  torch  in  the  hand  turns  the  tip  toward  the  left 
rather  than  the  right.  Left-handed  welders,  therefore,  will  do 

in 


112    .  WELDING   CAST   IRON 

just  the  reverse.  This  is  a  point  of  great  importance,  and  many 
defective  welds,  especially  in  heavy  sections,  are  due  to  neglect 
of  this  precaution. 

After  all  the  metal  necessary  has  been  added  (it  should  be 
enough  to  raise  the  weld  slightly  above  the  surrounding  sur- 
face), play  the  torch  flame  at  the  junction  of  the  old  and  new 
metal  until  the  new  metal  runs  into  the  old.  At  this  time,  do 
not  add  any  scaling  powder.  If  this  is  done  properly,  and  it 
should,  in  fact,  be  done  at  intervals,  as  the  weld  progresses, 
there  will  be  no  hard  spots  at  the  junction.  These  hard  spots 
are  caused  by  the  melted  metal  striking  a  colder  surface  and 
chilling.  They  may  be  caused,  even  with  the  utmost  care  on 
the  part  of  the  welder,  by  unsatisfactory  welding  material,  but 
with  good  material  and  care  they  will  not  exist.  The  scaling 
powder  has  nothing  to  do  with  them,  but  does  at  times,  if  of 
certain  compositions,  produce  a  thin  intensely  hard  scale,  which, 
however,  is  readily  removed  by  chipping  or  grinding. 

It  should  be  remembered  that  the  beginning  and  end  of  a 
weld  require  less  heat  than  the  middle,  because  there  is  not 
the  amount  of  metal  present  to  absorb  the  heat,  and  unless  care 
is  taken  to  keep  the  torch  somewhat  away  from  the  metal  at 
the  beginning  and  end,  the  tendency  will  be  to  burn  it;  also, 
at  these  points,  in  the  case  of  cast  iron,  there  is  a  tendency  for 
the  metal  to  run  away,  and  when  adding  metal  there,  the  torch 
flame  should  be  directed  toward  the  center  of  the  piece  rather 
than  toward  the  edge.  It  will  also  be  found  best  to  use  but 
little  scaling  powder,  as  the  slag  which  forms  on  the  surface  of 
the  iron  tends  to  hold  the  melted  metal  in  place.  In  many 
cases,  the  welding-rod  can  be  held  close  to  the  edge,  and  by 
manipulating  it  and  the  torch  the  metal  will  be  held  in  place. 

After  one  side  is  welded,  turn  the  work  over  and  repeat  the 
operation  on  the  other  side,  beginning  where  the  weld  on  the 
first  side  ended;  this  saves  gas.  After  the  sides  are  welded, 
it  is  advisable  to  touch  up  the  edges  so  that  the  metal  will  be 
welded  entirely  through  the  Vs.  Enough  metal  should  be  added 
so  that  the  piece  will  " square  up"  when  ground  to  its  original 
size,  and  care  should  be  taken  that  it  does  not  run  away.  Evi- 


WELDING  CAST  IRON  113 

dently  the  full  heat  of  the  torch  is  not  needed  at  these  points. 
In  the  case  of  a  small  weld  like  the  one  described,  there  will 
probably  be  no  casting  strains.  It  is  advisable,  however,  to 
take  the  precaution  of  heating  the  weld  uniformly  in  order  to 
be  sure  that  this  difficulty  does  not  exist.  After  the  weld  is 
finished,  allow  it  to  cool  off  in  a  dry,  warm  place. 

Finishing  and   Testing   the   Weld.  —  When   cold,   grind    or 
otherwise  remove  the  surplus  metal  to  the  same  size  as  the  origi- 


Fig.  1.  Welding  the  Broken  Flange  of  a  Cast-iron  Base.     The 
Operator  feeds  the  Joint  with  a  Cast-iron  Rod 

nal  casting,  and  put  it  in  a  vise  with  the  top  of  the  jaws  at  the 
center  of  the  weld.  If  the  weld  has  been  properly  made,  it  will 
be  found  impossible  to  break  the  piece  with  a  hammer,  except 
outside  of  the  weld.  It  should  be  necessary  to  break  off  the  piece 
at  both  ends  of  the  weld  and  then  break  the  weld  crosswise  (or 
lengthwise  of  the  original  piece)  to  see  what  the  fracture  looks 
like.  If  this  is  done,  it  will  be  noticed  that  the  weld  merges 
into  the  original  metal  without  any  distinct  line  of  demarcation, 
and  that  the  grain  of  the  weld  is  somewhat  finer  than  that  of 
the  casting;  also  that  the  color  is  slightly  different,  being  gener- 


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WELDING   CAST  IRON 

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is,  and  the  body  of  the  casting,  the  latter  being  somewhat  larger. 
This  difference  is  more  noticeable  in  a  larger  piece,  and  is  more 
apparent  in  the  piece  itself  than  in  the  illustration.  There  is  a 
small  projection  just  to  the  left  of  the  center  of  the  large  blow- 
hole, which  is  a  particle  of  foreign  matter,  probably  sand,  that 
gave  off  enough  gas  to  produce  a  blow-hole.  This  can  be  elim- 
inated in  welding  by  melting  to  the  bottom  of  the  hole  and 
floating  the  dirt  to  the 
surface. 

The  first  piece  welded 
by  a  beginner  will  prob- 
ably show  defects  caused 
by  the  metal  not  being 
thoroughly  melted  and 
only  sticking  together  in 
some  places  instead  of 
being  solid.  The  only 
way  to  gain  experience 
is  to  break  a  consider- 
able number  of  pieces 
and  repeat  the  trials  un- 


Fig.  3.    Weld  in  Cast  Iron  beveled  from  One 
Side.     Top  of  Weld 


til  a  sound  weld  is  easily 
made.  The  difficulty  in 
making  sound  welds  increases  with  the  size  of  the  piece,  and 
until  one  is  sure  that  he  can  make  good  welds  in  small  pieces, 
he  should  not  try  large  ones.  It  may  also  be  found  that  the 
proper  size  of  tip  is  not  used.  Too  small  a  tip  will  result  in 
cold  shuts  and  slow  work.  Too  large  a  tip  will  result  in  blow- 
ing the  metal  away  on  account  of  the  higher  oxygen  pressure 
used,  which  also  makes  the  work  slow,  and  tends  to  burn  out 
the  carbon  and  silicon  in  the  iron,  making  it  hard  and  brittle. 
The  proper  size  of  tip  can  be  found  after  a  few  trials,  and  ex- 
perience will  soon  teach  a  welder  what  tip  to  use  without  trial. 

General  Precautions  in  Welding.  —  In  making  welds  in  cast 
iron,  special  attention  should  be  paid  to  these  points:  Preheat 
the  work,  unless  it  is  a  small  piece,  or  of  very  simple  form,  for 
reasons  already  explained  in  Chapter  II.  Add  scaling  powder 


n6 


WELDING  CAST  IRON 


only  when  the  metal  does  not  flow  well,  and  even  then  use  no 
more  than  necessary.  Do  not  attempt  to  reweld  pieces  that 
have  been  previously  welded  or  brazed,  without  first  cutting 
away  all  of  the  old  metal.  When  the  weld  is  finished,  cover  it 
and  allow  it  to  cool  as  slowly  as  possible.  In  repair  work,  when 
beveling  the  edges,  it  is  sometimes  well  to  leave  a  few  small  points 
of  contact  for  aligning  the  broken  parts  in  the  original  position. 
Defects  in  Cast-iron  Welds.  —  As  an  illustration  of  the  defects 
that  are  likely  to  occur  in  a  cast-iron  weld,  the  piece  shown  in 

__     Figs.  3  to  6  was  prepared 

-  the  beveling  being 
done  from  one  side  only, 
and  the  piece  nicked 
with  a  hacksaw  and 
broken  in  order  to  show 
the  defects  more  clearly. 
Fig.  3  shows  the  front  of 
the  weld  or  the  top  as 
the  work  was  being  done, 
and  shows  how  the  weld 
should  be  made  in  steps 
in  order  to  prevent  cold 
shuts.  The  steps  extend 
from  A  to  B,  the  por- 
tion from  B  to  C  being 
welded  entirely  through,  some  of  the  metal  hanging  from  the 
bottom  of  the  weld  in  drops.  Fig.  4  shows  the  back  of  the 
weld,  and  it  will  be  noticed  that  from  A  to  B  the  original 
break  remains,  while  from  B  to  C  it  has  disappeared.  In  this 
view,  it  would  appear  that  the  weld  is  very  nearly  through,  but, 
upon  examining  Fig.  5,  it  will  be  found  that  it  is  not  through 
by  about  |  inch,  due  to  the  bridging  action  of  the  melted  metal 
heretofore  referred  to.  This  is  the  real  danger  of  a  weld  that  is 
not  burnt  through.  It  is  apparently  sound,  but  really  the  condi- 
tion is  much  worse  than  it  appears.  It  will  be  seen,  however, 
that  where  the  metal  has  been  burnt  through,  the  weld  is  perfectly 
sound.  At  C,  Figs.  5  and  6,  will  be  seen  a  spot  where  the  metal 


Fig.  4.   Weld  in  Cast  Iron  Tjeveied  from  One 
Side.    Bottom  of  Weld 


WELDING  CAST  IRON 


117 


has  run  over  from  the  added  material,  forming  a  cold  shut, 
which  is  very  distinct,  and,  of  course,  a  serious  source  of  weak- 
ness. In  addition  to  the  above,  it  will  be  seen  that  the  weld  is 
full  of  blow-holes  for  some  distance  from  the  bottom  of  the  V. 
These  were  caused  by  adding  metal  before  the  pieces  were  thor- 
oughly hot.  The  part  of  the  weld  which  is  level  with  the  original 
pieces  is  sound  at  the  top,  which  is  proof  that  while  a  weld  may 
be  sound 4to  all  appearances,  it  may  be  very  far  from  sound  inside. 

Example  of  Cast-iron 
Welds.  —  Fig.  7  shows 
a  cast-iron  exhaust  mani- 
fold with  one  of  the  bolt- 
ing lugs  broken  off.  This 
is  quite  a  frequent  occur- 
rence, and  is  generally 
due  to  the  sharp  corner 
left  when  the  nut-side  of 
the  lug  is  machined.  In 
order  to  keep  the  broken 
lug  straight  with  the  rest 
of  the  face,  a  planed  piece 
of  cast  iron  is  clamped 
across  the  face,  as  shown. 
It  is  best  to  weld  the  back 
of  the*lug  first  on  both  sides  of  the  clamp,  going  almost  through. 
Then  the  clamps  and  block  can  be  removed  and  the  job  finished. 

It  is  easier  in  many  cases  to  hold  such  pieces  in  a  vise  than  to 
block  them  up  on  the  table.  After  the  weld  is  made  on  the  out- 
side, the  inside  should  be  finished,  care  being  taken  to  burn  out 
all  remnants  of  the  crack.  The  last  thing  done  should  be  the  fin- 
ishing of  the  faces,  arid  care  should  be  taken  to  avoid  hard  spots. 
If  it  should  so  happen  that  the  lug  does  not  come  true  after 
the  weld  is  finished  (this  should  be  tested  with  a  straightedge), 
a  small  amount  of  metal  can  be  added  so  that  there  is  sufficient 
stock  to  grind  and  file.  The  finished  weld  is  shown  in  Fig.  8. 

Repairing  a  Machine  Frame.  —  Fig.  9  shows  the  frame  of  a 
machine  in  which  the  break  B  occurred  close  to  a  babbitt  bearing 


Fig.  5.   Weld  in  Cast  Iron  beveled  from  One 
Side,  but  Broken,  showing  Defects 


n8 


WELDING  CAST  IRON 


A .  It  was  decided  to  save  this  bearing  if  possible,  as  there  would 
have  been  considerable  expense  in  renewing  it,  not  so  much  on 
account  of  the  babbitt,  as  because  of  the  difficulty  of  alignment. 
No  finishing  was  necessary  at  the  weld.  This  made  it  much 
easier  to  save  the  babbitt,  because  even  if  a  few  hard  spots  did 


Fig.  6.   One  of  the  Pieces  in  Fig.  5  magnified  about  Three  Times 


Fig.  7.   Cast-iron  Manifold  on  which  Broken  Lug  is  to  be  welded 


Fig.  8.   Completed  Weld  of  Manifold  shown  in  Fig.  7 

exist  at  the  weld,  it  would  make  no  difference.  The  casting  was 
laid  flat  on  the  table,  the  parts  lined  up  after  preparation,  and 
preheated  with  a  Bunsen  burner,  during  which  time  wet  crushed 
asbestos  was  kept  on  both  the  top  and  bottom  of  the  babbitt 
bearing.  At  frequent  intervals  water  was  poured  on  the  asbestos 


WELDING   CAST  IRON 


IIQ 


to  keep  it  wet.  As  soon  as  the  casting  had  been  well  warmed, 
the  weld  was  made  on  one  side,  using  a  heavy  tip,  which  was 
necessary  on  account  of  the  absorption  of  heat  by  the  cool  metal. 
After  the  first  side  was  finished,  the  work  was  turned  over, 
repacked  in  wet  asbestos,  and  the  weld  completed.  The  weld 
was  then  heated  uniformly  its  entire  length  with  the  torch  and 
allowed  to  cool  in 
the  air.  Had  the 
break  occurred  at 
about  the  place 
where  the  rule  is 
shown,  it  would 
have  been  impossible 
to  save  the  babbit- 
ted bearing,  and  an 
entirely  different 
procedure  would 
have  had  to  be  fol- 
lowed. Undoubtedly 
the  babbitt  would 
have  been  melted 
out  and  care  would 
have  had  to  be  taken 
to  allow  for  the  con- 
traction of  the  weld. 
Two  torches  would 
have  been  advis- 
able, welding  both 
breaks  at  the  same 
time. 

Welding  a  Cast-iron  Crankcase.  —  Figs.  10  to  14  show  a  large 
cast-iron  crankcase  of  the  barrel  type,  with  a  piece  broken  out 
and  missing.  Fig.  10  shows  the  preparation  of  the  edges,  which 
was  done  prior  to  making  the  pattern  for  the  missing  piece. 
This  is  permissible  in  this  instance,  because  the  metal  is  cast  iron 
and  somewhat  over  J  inch  in  thickness,  and  also  because  the 
new  casting  used  in  repairing  was  made  with  enough  stock  on 


Fig.  9.   Machine  Frame  with  Babbitted  Bearing  close 
to  Weld 


120 


WELDING  CAST  IRON 


it  to  allow  for  finishing  on  the  hand-hole  face.  Fig.  n  shows 
the  asbestos  backing  for  the  pattern,  supported  by  a  sheet  of  iron 
and  a  mandrel  through  the  camshaft  bearing  holes,  this  being 
an  easy  way  of  supporting  the  backing  in  this  case.  Broken- 
up  asbestos  paper  is  now  used  altogether  in  the  author's  shops 
for  the  purpose  indicated,  on  account  of  the  ease  and  rapidity 


Fig.  10.   Cast-iron  Crankcase  in  which  Broken-out  Piece  is  Missing 


Fig.  11.  Asbestos  Backing  for  Plaster-of-l>aris  Pattern  in  Place 
in  Casting  shown  in  Fig.  10 

with  which  it  can  be  applied.  Prior  to  its  adoption,  it  was  the 
custom  to  use  plaster-of-paris,  trimming  it  off  to  the  inside 
surface  of  the  pattern  it  was  desired  to  make.  The  asbestos 
used  is  soaked  in  water  and  squeezed  out  until  it  is  just  plastic. 
It  is  then  pressed  into  place  and  smoothed  down  uniformly  to 
the  desired  level.  A  sheet  of  tissue  paper  is  then  placed  on  it 
and  oiled  to  prevent  the  plaster-of-paris  used  for  the  pattern 


WELDING   CAST   IRON  121 

from  sticking  to  it.  The  plaster-of-paris  is  next  poured  into 
place,  and,  as  it  gradually  hardens,  it  is  brought  to  the  required 
contour  and  allowed  to  dry.  The  result  is  shown  in  Fig.  13, 
in  which  it  will  be  noted  that  sufficient  stock  for  finishing  has 
been  left  on  the  hand-hole  face  of  the  casting,  and  that  the 
plaster-of-paris,  while  hardening,  has  been  beveled  out  to  make 
the  V.  A  gentle  tapping  on  the  casting  around  the  pattern 
loosens  it,  so  that  it  may  be  lifted  out  without  breakage.  Care 
should  be  exercised  at  this  stage  of  the  operation,  and  the  plaster- 
of-paris  should  be  allowed  to  become  quite  hard,  although  it 
need  not  be  entirely  dry.  Upon  removal,  air-holes  and  irregu- 
larities on  the  inside  face  will  be  found,  and  they  should  be  filled 


Fig.  12.   Casting  that  is  to  be  inserted  in  Place  of  Broken-out 
Piece  in  Fig.  10 

up.    Attention  should  also  be  paid  to  so  making  the  pattern 
that  it  can  be  drawn  from  the  sand. 

The  casting  made  from  this  pattern  is  shown  in  Fig.  12,  and 
the  welded  job  in  Fig.  14.  This  job  was  welded  in  a  large  forge, 
the  break  being  turned  downward  into  a  charcoal  fire,  allowed 
to  become  nearly  fed-hot,  turned  over,  carefully  covered  with 
asbestos  paper  and  welded,  but  only  from  the  outside,  as  it  was 
not  necessary  from  the  standpoint  of  strength  to  do  more  than 
this.  The  weld,  of  course,  was  made  entirely  through  the  section, 
and  what  beads  resulted  were  chipped  off  after  the  case  was  cold. 
After  welding,  the  weld  was  turned  into  the  fire  again,  allowed 
to  come  to  a  uniform  temperature,  and  then  packed  in  asbestos 
to  cool.  In  this  instance  it  was  not  necessary  to  heat  the  entire 
casting  to  the  same  high  temperature,  but  the  casting  was  all 
hot,  the  coolest  part  being  at  a  temperature  much  above  that  of 
boiling  water.  It  is  one  of  the  instances  where  it  is  not  necessary 
to  heat  the  whole  casting  to  as  high  a  temperature  as  the  part 
to  be  welded,  nor  indeed  is  it  desirable  to  do  so.  The  case  is 
stiff  enough  to  gradually  force  the  contraction  to  take  place  in 


122 


WELDING  CAST   IRON 


the  weld  as  it  is  made,  and,  by  allowing  it  to  come  to  a  uniform 
high  temperature  after  the  weld  is  finished,  any  strains  that  may 
be  caused  in  welding  are  eliminated. 

Welding  a  Shaper  Rocker  Arm.  —  Fig.  1 5  shows  a  cast-iron 
arm  from  a  shaper.  An  attempt  was  made  to  weld  this  arm 
by  someone  without  either  the  necessary  knowledge  or  facilities, 
with  unsatisfactory  results.  The  weld  at  A  and  the  opening 
at  B  showed  that  the  weld  did  not  extend  in  more  than  J  inch. 


Fig.  13.   Plaster-of-paris  Pattern  Completed 


Fig.  14.  Weld  Completed 

The  work  had  not  been  preheated  or  prepared.  The  photograph 
was  taken  after  the  break  at  C  was  partly  prepared  at  the  author's 
shop.  The  essential  thing  in  this  piece  was  to  make  the  edges 
of  the  slots  D,  which  form  a  fork  at  the  end  of  the  casting,  come 
at  right  angles  to  the  surfaces  E  and  F,  and  also  to  have  these 
two  surfaces  in  line.  It  was  necessary  also  to  be  sure  that  the 
surfaces  H  and  7  were  parallel,  as  a  sliding  block  operates  be- 
tween them.  The  method  of  doing  this  was  to  clamp  the  piece 


WELDING   CAST   IRON  123 

on  the  corner  of  the  welding  table,  as  shown  in  Fig.  16.  In  order 
to  remove  the  chill  from  the  casting  to  some  extent,  a  Bunsen 
burner  as  shown  at  A  was  directed  against  the  break  at  B.  The 
upper  half  of  the  weld  was  made,  the  casting  turned  over  and 
blocked  up  carefully,  and  the  weld  finished.  It  was  then  tested 
to  see  that  everything  was  straight  and  square.  It  was  found  to 
be  in  good  shape,  but  if  it  had  not  been,  the  difficulty  would  have 


Fig.  15.   Shaper  Rocker  Arm  broken  in  Three  Places.     This  Arm  had 
been  improperly  welded  and  broke  again 


Fig.  16.   Method  of  Holding  Rocker  Arm  while  Welding 


been  corrected  by  heating  the  weld  B  with  a  large  torch,  when 
the  piece  C  could  be  carefully  pulled  into  position  by  means  of 
wedges  and  clamps.  The  weld  was  allowed  to  cool  and  the  piece 
blocked  up  on  the  table  as  shown  in  Fig.  17,  all  the  surfaces  on  the 
lower  side  being  laid  on  V-blocks  of  the  same  height.  The  fork- 
end  was  then  clamped  into  position  so  that  the  slots  were  true 
with  a  square  both  ways  and  the  top  half  of  the  weld  E  made, 


124 


WELDING   CAST  IRON 


It  should  be  noticed  that  there  was  enough  of  the  finished 
surfaces  underneath  B  and  C  to  allow  a  narrow  V-block  to  be 
set  underneath  which  held  it  true  in  one  plane,  while  blocking 
was  put  under  the  fork  to  hold  it  true  in  the  other  direction.  Of 
course,  the  piece  was  clamped  down  to  the  table,  while  the  first 
part  of  weld  E  was  being  made.  It  was  then  turned  over  and 
the  weld  finished,  and  the  piece  again  tested  to  see  that  it  was  in 


Fig.  17.   Blocking  used  to  insure  Proper  Alignment  of  Welded  Parts 
while  making  Final  Weld 


Fig.  18.   Completed  Rocker  Arm  properly  welded 

good  condition.  It  is  evident  that  after  these  operations  the 
piece  was  true  and  in  line,  and,  with  reasonable  care,  would 
remain  so.  There  was,  however,  danger  of  a  strain. in  making 
the  last  weld.  This  was  overcome  by  putting  tram-marks  at  A 
and  B,  Fig.  18,  and  heating  the  opposite  side  in  a  charcoal  fire 
sufficiently  to  give  the  necessary  expansion,  which  was  checked 
by  the  tram-marks.  The  piece  was  carefully  blocked  up  so  that 
no  sagging  would  take  place,  and  half  the  weld  made.  It  was 
then  turned  over  and  the  weld  finished,  the  piece  removed  from 


WELDING  CAST?  IRON  I $5 

the  fire  and  allowed  to  cool  down  in  asbestos.  The  conditions 
required  that  all  of  these  welds  be  made  without  heating  the 
piece  red-hot,  because  it  would  have  been  very  difficult  to  keep 
the  parts  in  line,  had  the  whole  piece  been  put  in  a  hot  fire. 

One  difficulty  in  this  case  was  that  all  of  the  faces  were  more 
or  less  worn,  and  some  judgment  had  to  be  used  in  checking 
them  up.  However,  the  piece  after  finishing  gave  entire  satis- 
faction. The  use  of  small  torches  or  gas  burners  in  this  or 
similar  cases  is  of  great  assistance,  because  while  they  do  not 
bring  the  piece  to  a  red  heat,  yet  enough  of  the  chill  is  taken  from 
the  metal  to  save  a  considerable  amount  of  welding  gases,  and 
this  also  helps  to  make  a  better  weld.  It  is  evident  that  it  would 
be  quite  difficult,  if  not  impossible,  to  block  up  such  a  piece  on 
the  table  and  build  up  a  charcoal  fire  under  it,  the  heat  being 
likely  to  warp  or  crack  the  table. 

Oxy-acetylene  Welding  as  a  Means  of  Repairing  Cylinders. 
-  Breakages  in  automobile  cylinders  can  be  divided  into  three 
main  classes  which  cover  at  least  ninety  per  cent  of  the  cases. 
The  majority  of  these  breakages  can  be  satisfactorily  repaired 
by  means  of  the  oxy-acetylene  flame,  the  cylinder  being  as  good 
as  new.  Additional  metal  is  added  where  necessary  from  a  rod 
of  the  same  material,  and  the  process  consists  in  practically 
recasting  the  part  locally.  Oxy-acetylene  welding  is  proving 
a  great  boon  to  those  who  are  unfortunate  enough  to  have  their 
automobile  cylinders  broken,  as  they  can  be  satisfactorily 
welded,  and  in  the  majority  of  cases,  with  a  little  trimming  off, 
the  repairs  will  not  show.  Cylinders  with  cracks  were  formerly 
sometimes  brazed,  but  owing  to  the  necessity  of  heating  the  whole 
cylinder  to  a  good  red  heat  to  even  up  the  contraction  strains, 
so  as  not  to  crack  when  cooling,  the  bore  of  the  cylinder  was  gen- 
erally warped,  and  the  job  required  a  lot  of  finishing,  as  the 
spelter  and  flux  spread  considerably  and  were  difficult  to  re- 
move. Also,  owing  to  the  dirt  and  rust  in  the  crack,  it  was  diffi- 
cult to  get  the  brazing  below  the  surface;  the  high  temperature 
necessary  would  sometimes  crack  the  cylinder  elsewhere. 

Water  Jackets  Broken  by  Freezing.  —  In  the  early  days  of 
the  automobile,  the  largest  class  of  cylinder  breakages  —  mainly 


126 


WELDING  CAST   IRON 


due  to  carelessness  —  was  caused  by  allowing  the  water  jacket 
to  freeze,  resulting  in  the  breaking  of  the  water-jacket  wall. 
Also,  it  frequently  happened  that  when  shipping  a  car  by  rail 
in  winter  the  drain  cocks  were  opened,  but  due  to  some  pocket 
in  the  water  system  (in  some  cases  very  small  ones)  which  did 
not  drain,  the  cylinders  broke  from  the  freezing  of  the  water. 
The  cause  was  really  to  be  found  in  the  faulty  design  of  the 
water  cooling  system,  and  troubles  of  this  kind  are  seldom  or 
never  met  with  nowadays.  The  cylinders  A  and  B,  Fig.  19, 


Fig.  19.   Two  Cylinders  with  Cracked  Water  Jackets  prepared  for 
Welding.     Twin  Cylinders  with  Broken  Flanges  to  be  Welded 

show  common  types  of  breakages  which  were  satisfactorily 
welded  every  day,  a  few  years  ago.  The  crack  in  A  is  17 
inches  in  length.  -  , .  -,  . 

Cylinder  Wall  Broken.  —  Another  class  of  breakages  is  that  in 
which  the  wall  of  the  cylinder,  combustion  or  valve  chamber,  is 
broken  or  cracked.  This  class  of  breakages  is  difficult  to  repair, 
as  it  is  necessary  in  most  cases  to  cut  out  a  section  of  the  water 
jacket  to  be  able  to  work  on  the  inner  wall,  the  only  exception 
occurring  when  the  break  happens  to  be  opposite  a  large  hand- 


WELDING  CAST  IRON  127 

hole.  As  it  often  is  impossible  to  determine  the  length  or  exact 
locality  of  the  cracks  before  cutting  away  the  jacket,  and,  as 
it  is  desirable  to  remove  as  small  a  section  as  possible,  it  often 
is  found  necessary  to  cut  out  additional  pieces,  thus  necessitat- 
ing welding  a  number  of  small  pieces  back  in  place  when  finish- 
ing the  job.  To  restore  these  pieces  sometimes  is  impracticable, 
and  a  sheet  steel  substitute  has  sometimes  been  used;  this  is 
hammered  out  and  welded  in  place.  With  care,  this  piece  can 
be  shaped  so  as  to  coincide  with  the  piece  removed,  and  cannot 


Fig.  20.  Cylinder  A  repaired  by  inserting  a  Steel  Piece,  bent  to 
Shape,  and  Autogenously  Welded  in  Place.  Cylinder  B  has  had 
Flange  repaired 

be  detected  when  welded  in  place.  The  part  cut  away  was  thus 
neatly  replaced  by  sheet  steel,  as  shown  at  A,  Fig.  20.  It  is 
better,  and  generally  easier,  however,  to  build  up  the  jacket 
solid,  when  the  original  pieces  cannot  be  used. 

The  cover  plate  on  the  cylinder  shown  in  Fig.  20  was  also 
broken  at  the  same  time  as  the  cylinder  wall  was  broken,  and  is 
shown  welded.  Fig.  21  shows  a  cylinder  having  a  crack  8  inches 
long,  located  at  the  corner  of  the  combustion  head,  that  was 
welded.  The  part  cut  out  of  the  water  jacket  is -also  shown.  It 
will  be  noticed  that  this  operation  required  cutting  through  a 
supporting  lug. 


128  WELDING  CAST  IRON 

Broken  Flanges.  —  Other  common  breakages  are  those  in 
which  all,  or  a  portion  of  the  flange,  which  holds  the  cylinder  to 
the  crankcase  is  broken  away,  due  either  to  insufficient  metal 
to  withstand  the  strain  or  to  carelessness  in  assembling.  These 
breakages  occur  in  two  ways;  the  wall  of  the  cylinder  may  be 
broken  away  or  part  of  the  flange  may  be  cracked  off.  In  the 
latter  case,  it  is  an  easy  matter  to  make  the  repair,  but,  when  the 
break  runs  through  into  the  bore  of  the  cylinder,  considerable 
care  is  required.  First  it  is  necessary  to  consider  whether  it 
is  desirable  to  weld  in  the  bore,  which  would  then  require  machin- 


Fig.  21.    Cylinder  Cracked  in  Inner  Wall,  Fig.  22.  Air-cooled  Cylin- 

showing  Large    Section  of  Outer   Wall  der  on  which  Boss  for 

removed  to  Weld  the  Crack  by  the  Oxy-  Ignition  Plug  was  Au- 

acetylene  Torch  togenously  welded 

ing  or  at  any  rate  filing  out,  or  only  groove  and  weld  from  the 
outside  to  within  Ye  mcn  °f  the  bore,  sufficient  metal  being  added 
to  the  outside  to  insure  strength.  The  latter  method,  of  course, 
leaves  the  crack  on  the  inside,  which  can,  however,  be  smoothed 
down  and  is  not  objectionable  for  a  repair  job,  as  it  does  not  inter- 
fere with  the  satisfactory  operation  of  the  motor  in  any  way; 
but  a  more  serious  objection  is  that  such  a  repair  weld  frequently 
breaks  again,  and  the  author  has  abandoned  the  practice,  and 
for  years  has  welded  all  such  parts  inside  as  well  as  outside. 

In  addition,  there  is  a  large  variety  of  other  breakages,  no  two 
of  which  are  alike,  that  can  be  repaired  successfully  by  the  oxy- 
acetylene  torch.  Considerable  welding  can  also  be  carried  out 


WELDING  CAST  IRON 


by  the  manufacturer,  such  as  the  welding  on  of  additional  bosses 
for  dual  ignition  systems,  as  shown  in  Fig.  22,  building  up  bosses 
that  did  not  "fill"  in  castings,  etc. 

Repairing  a  Broken  Cylinder  Casting.  —  Fig.  23  shows  what 
frequently  happens  when  some  part  of  the  connecting-rod  in 
a  motor  gives  away.  This  damage  is  generally  the  result  of  not 
keeping  the  rods  tightened  up  as  they  should  be.  The  case 


Fig.  23.   Automobile  Cylinder  with  Dome  broken  and  Jacket  cut 
away  in  Order  to  Reach  Broken  Portions 

illustrated  is  not  nearly  as  bad  as  some  instances,  but  great  care 
must  be  exercised  in  following  the  crack  to  the  end.  If  the  crack 
extends  entirely  through  a  piece,  it  will  prevent  the  heat  of  the 
torch,  when  applied  to  one  side,  from  passing  to  the  other,  with 
the  result  that  where  the  piece  is  heated  it  will  become  red,  while 
the  other  side  will  stay  black;  but  if  the  crack  extends  only  partly 
through,  as  is  frequently  the  case,  this  test  is  valueless,  and  the 
only  thing  to  do  is  to  melt  the  iron  in  the  direction  in  which  the 


WELDING  CAST  IRON 


crack  extends  and  pull  it  out  with  the  welding-rod.  If  there  is 
a  crack,  it  will  show  up  as  a  white  streak  in  the  center  of  the 
melted  portion.  Therefore,  in  all  cases  of  this  character,  and  in 
the  case  of  jacket  cracks,  the  weld  should  be  made  entirely 
through  the  piece  at  least  i  inch  farther  than  the  crack  shows  on 
the  surface,  in  order  to  be  sure  that  the  end  is  reached.  In  the 
present  instance  the  crack  at  corner  A  extended  f  inch  beyond 


Fig.  24.    Automobile  Cylinder  shown  in  Fig.  23  after  Dome 
has  been  welded 

where  it  was  visible.  The  pieces  were  not  prepared,  nor  is  it 
the  practice  in  the  author's  shops  to  V  the  pieces  in  such  cases. 
Preheating  of  Cylinder.  —  Cylinders  should  always  be  heated 
slowly,  and  the  base  of  the  cylinder  kept  somewhat  away  from 
the  fire,  which  should  not  be  too  heavy  at  the  beginning.  The 
cylinder  should  be  tilted  at  an  angle  so  that  the  heat  will  pass 
up  through  the  bore  and  around  the  outside,  underneath  the 
asbestos  paper  with  which  it  is  covered.  After  the  work  is 
thoroughly  warmed  through,  the  defective  part  should  be  placed 


WELDING  CAST  IRON 

in  the  fire  so  as  to  become  more  thoroughly  heated  than  the 
remainder.  At  this  stage  the  heating  should  be  watched  care- 
fully, and  when  it  has  arrived  at  the  proper  point,  while  the 
temperature  is  still  rising,  it  should  be  welded  in  the  fire.  Under 
no  circumstances  must  a  cylinder  be  removed  from  the  fire 
while  the  weld  is  being  made,  and  sufficient  asbestos  paper  should 


Fig.  25.   Cylinder  shown  in  Fig.  23  with  Piece  of  Jacket  set  in 
Place  ready  for  Welding 

be  properly  located  to  cover  all  the  cylinder  except  the  part  being 
worked  upon. 

It  is  very  difficult  to  explain  how  hot  to  heat  a  cylinder.  If 
possible  to  avoid  it,  the  heat  should  not  be  great  enough  to  make 
it  red  at  any  point.  In  certain  cases  the  cylinder  must  be  heated 
to  a  red  heat,  particularly  where  there  is  a  rigid  connection  be- 
tween the  barrel  and  the  jacket  at  several  points,  or  where  the 
cylinders  have  large  flat  sides.  Frequently  the  proper  tempera- 
ture can  be  determined  by  the  paint  and  filler  on  the  cylinder 
being  turned  to  a  rusty  brown  powder.  This  test  is  only  of  value 


13 2  WELDING  CAST  IRON 

when  the  cylinder  is  on  a  rising  temperature.  It  is  evident,  if 
it  has  been  heated  to  this  point  and  then  allowed  to  cool,  that  it 
may  not  be  warm  enough  to  avoid  shrinkage  cracks,  while  it  may 
appear  so  to  the  eye.  The  best  way  to  obtain  experience  is  to 
get  some  old  cylinders  and  experiment  with  them.  More  can 
be  learned  in  this  way  in  a  short  time  than  by  pages  of  description. 


Fig.  26.-  Cylinder  Jacket  with  Crack      Fig.    27.     Jacket  with   Crack 
not  Visible  from  Outside  Clearly  Visible  from  Inside 

The  Welding  Operation.  —  In  this  case,  as  soon  as  the  cylinder 
arrived  at  the  right  temperature,  which  was  higher  than  for  an 
ordinary  jacket  crack  —  very  close  to  a  red  heat  —  it  was  turned 
into  the  position  shown  in  Fig.  23,  and  the  pieces  welded  on. 
The  welding  began  at  A,  went  from  there  to  B  and  C,  and  so 
on  back  to  the  starting  point.  This  gave  the  maximum  chance 
for  contraction  to  take  place  without  difficulty.  The  weld  was 
burnt  completely  through,  and,  as  soon  as  finished,  the  cylinder 
was  turned  over  in  the  fire  and  the  inside  of  the  weld  completed 


WELDING   CAST   IRON 


and  smoothed  off  with  a  special  torch.  This  is  necessary  in  order 
to  prevent  preignition  in  operation  due  to  small  points  project- 
ing into  the  cylinder  becoming  red  hot,  or  to  carbon  collecting 
on  such  points  and  causing  the  same  trouble.  It  is  sometimes 
necessary  to  have  more  than  one  special  torch  to  reach  all  the 
corners.  Occasionally  a  cylinder  broken  -in  the  dome  is  split 
part  way  down  the  barrel.  The  only  satisfactory  way  of  repair- 


Fig.  28.  Improperly  Welded  Cylinder 

ing  such  a  crack  is  to  weld  from  both  sides,  and  then  re-grind 
the  cylinder. 

After  the  dome  was  welded,  the  cylinder  was  packed  away 
in  powdered  asbestos  until  cold;  the  proper  openings  were  then 
plugged  and  the  cylinder  tested  for  leaks.  This  is  always  a 
proper  precaution,  because  while,  if  the  work  is  properly  done, 
there  is  little  chance  for  trouble,  yet,  if  there  is  any  difficulty 
or  if  any  crack  is  overlooked,  it  can  be  welded  much  more  easily 
than  if  the  jacket  is  welded  right  away.  However,  when  time  is 


134  WELDING   CAST   IRON 

an  object,  as  it  occasionally  is,  and  if  the  welder  is  sure  that 
he  has  welded  the  dome  properly,  the  jacket  may  be  welded 
at  once,  the  whole  cylinder  packed  in  asbestos  and  allowed  to 
cool. 

After  the  cylinder  was  tested  and  everything  found  satis- 
factory, it  was  reheated,  the  jacket  put  in  place  as  shown  in  Fig. 
25  and  welded,  beginning  at  A  and  going  to  B,  after  which  it 
was  welded  around  the  boss,  again  started  at  B,  and  continued 
around  to  C.  This  took  care  of  the  contraction  better  than  any 
other  method.  The  surface  C  was  set,  before  starting  to  weld, 


Fig.  29.  Rough  Condition  of  Inside  of  Dome  of  Improperly 
Welded  Cylinder 

a  little  higher  than  D  to  allow  of  finishing  the  boss  around  the 
center-hole. 

Mention  has  been  made  of  the  possibility  of  a  crack  extending 
on  the  inside  of  a  piece  where  it  is  not  visible  on  the  outside.  A 
good  illustration  of  this  is  shown  in  Figs.  26  and  27,  which  show 
a  piece  broken  out  of  an  automobile  cylinder  jacket  in  order  to 
weld  the  dome.  In  Fig.  26,  a  crack  was  visible  at  the  top  and 
bottom  of  the  piece  as  a  very  fine  line,  but  it  was  not  visible  for 
more  than  f  inch  in  either  case  on  the  outside  of  the  piece.  How- 
ever, it  will  be  noticed  that  it  extends  along  and  is  quite  clearly 
visible  inside  in  Fig.  27.  This  condition  may  exist  not  only 
in  cylinder  jackets,  but  in  many  other  pieces,  both  large  and  small, 
and  the  illustrations  are  shown  to  emphasize  the  necessity  of 
following  the  crack  all  the  way  to  the  end. 


WELDING   CAST   IRON 


13S 


Defective  Welding  of  Cylinders.  —  As  an  illustration  of  what 
results  from  improper  welding  of  cylinders,  Figs.  28  to  30  are 
shown.  The  original  damage  to  this  cylinder  is  indicated  in 
Fig.  28,  and  consisted  of  a  crack  in  the  dome.  From  the  appear- 
ance of  the  inside  of  the  cylinder  shown  in  Fig.  29,  the  dome 
appears  to  be  broken  in  a  number  of  pieces.  It  does  not  appear 
on  examination  of  the  cylinder  whether  the  jacket  was  cut  out 
in  order  to  reach  the  broken  dome,  or  whether  it  was  broken  out 
originally  by  the  damage.  However,  in  attempting  to  put  it 
back,  the  cracks  kept  on  extending  until  the  cylinder  was  cracked 


Fig.  30.   Contraction  Cracks  in  an  Improperly  Welded  Cylinder 

through  two  port  plug  holes.  In  addition  to  this,  the  corner 
of  the  cylinder  as  welded  was  much  flatter  than  it  should  be, 
the  result  being  that  it  would  have  been  impossible  to  grind 
out  the  cylinder  without  going  through  the  weld.  In  addition 
to  the  above,  there  was  no  attempt  made  to  smooth  off  the  inside 
of  the  dome,  with  the  result  that  the  cylinder  would  have  knocked, 
on  account  of  preignition  due  to  the  roughness.  The  cylinder 
as  it  stands  is  not  beyond  repair,  if  handled  properly,  but  the 
owner  purchased  a  new  cylinder,  believing  that  it  could  not  be 
fixed. 


136  WELDING   CAST   IRON 

This  is  a  good  instance  of  the  damage  to  the  reputation  of  the 
oxy-acetylene  welding  process  caused  by  those  who  do  not  know 
how  to  do  the  work  and  who  have  not  the  proper  facilities. 
This  cylinder  was  not  preheated.  The  possession  of  a  hammer, 
chisel,  and  monkey  wrench  does  not  make  the  owner  a  machinist; 
neither  does  the  fact  that  one  has  a  welding  torch  and  oxygen 
and  acetylene  tanks  enable  him  to  weld  anything  that  comes 
along.  It  should  be  emphasized  that  proper  apparatus,  instruc- 
tions)  and  training  are  necessary  for  the  successful  carrying  out 
of  work  such  as  that  shown. 


Fig.  31.   Cylinder  badly  damaged  and  Jacket  cut  away  to  Enable 
Welding  to  be  done 

Properly  Welded  Cylinder.  —  As  a  contrast  to  the  foregoing, 
Figs.  31  to  34  are  shown.  Fig.  31  shows  the  damage  to  the  dome, 
and  the  pieces  of  the  jacket  cut  away  to  reach  it.  Fig.  32  shows, 
on  the  right,  the  pieces  of  the  dome,  and  on  the  left  the  pieces 
of  the  jacket.  In  the  center  is  shown  the  plug  going  through  the 
top  of  the  dome  and  jacket.  It  will  be  seen  that  the  thread  on 
this  is  badly  damaged.  The  dome  was  broken  into  twelve  pieces 
and  the  jacket  into  eight  pieces.  At  A,  B,  C,  and  D  are  shown 
the  points  where  the  four  ribs  extending  between  the  dome  and 
jacket  are  located,  the  ribs  themselves  not  being  shown. 


WELDING   CAST   IRON 


137 


The  pieces  are  shown  laid  together  on  wet  asbestos  and  care- 
fully lined  up.  They  were  then  "tacked"  together  with  the 
torch  so  that  they  could  be  used  as  patterns  for  castings,  the 
cost  of  welding  all  the  pieces  together  being  too  great;  besides, 
it  would  be  difficult  to  put  the  pieces  accurately  into  place. 
On  the  castings  from  these  patterns,  as  shown  in  Fig.  33,  stock 
was  left  for  finishing,  except  at  the  points  A,  B,  C,  and  D,  where 


Fig.  32.   Pieces  of  Broken  Dome  and  Jacket  of  Cylinder 
shown  in  Fig.  31 


Fig.  33.   Castings  used  in  Making  Repairs  shown  in  Figs.  34  and  35 

the  connecting  ribs  between  the  dome  and  jacket  had  to  be  built 
up.  Fig.  34  shows  the  dome  welded  in.  Fig.  35  shows  the  jacket 
welded  in  and  the  dome  plug  with  metal  added  on  the  threads. 
All  the  machining  was  done  on  an  ordinary  lathe.  It  was  not 
possible  to  obtain  exactly  the  same  thread  on  the  dome  plug 
as  on  the  original,  but  this  made  no  difference,  as  the  stock 
allowed  permitted  any  suitable  thread  to  be  used,  It  was  im- 


138  WELDING  CAST  IRON 

possible  in  this  case  to  obtain  a  new  cylinder,  as  the  manu- 
facturers had  gone  out  of  business;  but  the  cost  of  repairs  was 
considerably  less  than  the  cost  of  a  new  cylinder. 

Even  though  there  may  be  no  foundry  near,  the  welding  of 
the  pieces  together  and  setting  them  back  into  place  is  perfectly 
possible.  They  should  all  be  welded  together  on  both  sides, 
the  inside  of  the  dome  smoothed  off  by  grinding,  fitted  in  place, 


Fig.  34.   Dome  welded  in  Place 


Fig.  35.   Jacket  welded  in  Place 

and  welded.  In  such  cases,  enough  of  the  jacket  should  be  cut 
away  at  the  beginning  to  enable  the  work  to  be  done  rapidly,  and 
the  planning  should  be  done  ahead,  so  that  it  will  be  known 
exactly  how  the  work  is  to  be  handled.  There  is  no  necessity 
of  having  to  plan  these  things  while  the  work  is  being  done. 

Welding  a  Heating  Boiler  Casting.  —  Figs.  36  to  40  show  a 
section  of  a  cast-iron  heating  boiler.    Quite  a  number  of  these 


WELDING   CAST   IRON  139 

heater  sections  break,  and  as  they  are  expensive,  they  are  well 
worth  welding.  The  reasons  for  their  breaking  generally  come 
under  three  heads:  i.  Allowing  the  water  to  become  too  low 
in  the  boiler.  This  permits  the  section  to  become  red-hot,  and, 
when  it  is  cooled  off,  or  cold  water  turned  in,  a  crack  results. 
2.  Casting  strains  in  the  pieces.  The  author  has  seen  new  sec- 
tions not  yet  installed  with  bad  cracks  which  could  not  have 


Fig.  36.   Crack  in  Section  of  a  Cast-iron  Heating  Boiler 

passed  inspection  at  the  foundry.  Sometimes,  upon  inquiry 
about  a  cracked  section,  the  statement  is  made  positively  that 
the  water  was  not  low,  and  while  this  statement  may  not  always 
be  true,  yet  a  sufficient  number  of  cases  have  come  to  the  author's 
attention  in  which  he  believes  the  information  to  have  been 
correct,  to  warrant  the  belief  that  strains  hi  the  casting  are 
really  a  frequent  cause  of  breakage.  It  is  also  well  known  that 
it  is  difficult  to  cast  pieces  of  the  shape  of  these  sections  without 


140  WELDING   CAST   IRON 

experiencing  casting  strains  due  to  the  difference  in  temperature 
of  different  parts  while  cooling  off  in  the  sand.  3.  Strains  are 
sometimes  caused  by  the  holes  for  the  push  nipples,  which  con- 
nect the  sections,  not  being  bored  true,  or  in  line;  or,  if  the 
sections  are  not  put  up  correctly,  the  same  trouble  may  exist. 
It  is  also  possible  to  pull  the  sections  together  too  tightly,  and,  as 
the  push  nipples  are  tapered  and  fit  in  tapered  holes,  an  enormous 
strain  can  be  set  up  by  too  much  tightening. 

Difficulties  in  Welding  Heater  Sections.  —  Cracked  heater 
sections  are  generally  very  difficult  to  weld,  particularly  if  the 
cracks  are  in  the  body  of  the  section.  If  only  a  corner  is  broken 
off,  or  if  the  section  has  a  long  leg  on  each  side  and  the  defect 
is  in  one  of  them,  the  difficulty  is  materially  decreased.  Con- 
siderable experience  is  required  to  make  a  sound  permanent 
job,  and  even  then  satisfactory  results  may  not  be  obtained  at 
the  first  trial.  The  difficulties  met  with  are  the  trouble  of  con- 
trolling the  contraction  when  cooling,  and  of  preheating  correctly, 
as  well  as  the  trouble  of  turning  the  section  over  while  hot  in 
order  to  reach  the  other  side  of  the  weld. 

In  order  to  overcome  these  difficulties,  it  is  necessary,  in  the 
first  place,  to  heat  the  entire  section  red-hot;  this  heat  must  also 
be  uniform.  It  is  believed  to  be  useless  to  spend  time  trying  to 
heat  such  a  casting  locally,  or  to  provide  for  contraction  by 
heating  one  part  somewhat  more  than  another.  The  cause  of 
the  crack  cannot  always  be  known,  and  inasmuch  as  the  real 
cause  may  be  a  combination  of  causes,  the  only  safe  way  is  to 
eliminate  all  strains  by  thoroughly  preheating  to  a  high  tempera- 
ture. The  contraction  while  cooling  may  be  overcome  by  slow 
cooling  obtained  by  packing  the  welded  casting  in  asbestos  and 
thoroughly  protecting  it  from  drafts.  In  the  case  of  large 
sections,  this  cooling  may  require  forty-eight  hours.  If  the  work 
is  to  be  done  outside,  in  cold  weather,  great  precautions  must 
be  taken  to  insure  that  the  outside  edges  of  the  casting  do  not 
cool  too  quickly. 

The  difficulty  of  turning  over  the  casting  can  best  be  over- 
come by  providing  special  means  for  handling.  What  is  done 
depends  upon  conditions,  and  no  fixed  rule  can  be  laid  down; 


WELDING  CAST  IRON  141 

but  the  casting  must  be  handled  quickly,  and  if  it  is  turned 
over,  it  must  be  allowed  to  reach  a  uniform  temperature  before 
the  final  weld  is  made.  After  welding,  the  casting  should  again 
be  brought  to  a  uniform  temperature,  and  then  carefully  packed 
as  outlined. 

Preparation  for  Welding.  —  Fig.  36  shows  a  section  in  which 
the  crack  was  probably  caused  by  an  original  strain  in  the  casting. 


Fig.  37.  Heating  Boiler  Casting  prepared  for  Welding 

The  crack  was  barely  visible,  and,  in  order  to  show  in  the  photo- 
graph, it  was  necessary  to  wedge  it  open  somewhat.  There  was 
some  discussion  in  the  shop  as  to  just  how  to  prepare  the  crack 
for  welding.  It  was  manifestly  impossible  to  get  any  torch 
tip  into  the  hole,  which  is  about  i  inch  in  diameter,  as  the  section 
was  about  4  inches  thick  at  that  point.  It  was  finally  decided 
to  prepare  the  casting  as  shown  in  Fig.  37,  saving  the  piece 
that  was  cut  out  (the  cutting  being  done  by  a  hacksaw  and 


142  WELDING  CAST  IRON 

hammer  and  chisel) ,  so  that  it  could  be  replaced.  The  advantage 
of  this  method  was  apparent  when  the  piece  was  removed,  as 
it  was  found  that  there  was  a  boss  ij  inch  thick  around  the  i- 
inch  hole,  the  piece  cut  out  of  the  boss  being  shown  in  Fig.  37,  at 
A,  while  the  main  piece  removed  is  seen  at  B.  The  boss  can  be 
seen  in  Fig.  39,  where  the  section  is  shown  laid  on  steel  plates, 
blocked  up  from  the  concrete  floor  and  with  firebricks  under 


Fig.  38.  Heating  Boiler  Casting  in  which  Weld  is  finished 

the  corners  to  leave  space  for  the  fire.  The  tram-marks  will 
also  be  noticed  at  A,  B,  and  C,  the  distance  AC  being  equal  to 
ABj  and  being  used  as  a  reference  length. 

Preheating  the  Casting.  —  Fig.  40  shows  the  use  of  old  car- 
bide cans  cut  up  into  strips  of  the  proper  size  for  confining  the 
fire.  These  are  very  satisfactory  for  the  purpose,  as  they  can 
readily  be  bent  to  any  shape  and  are  inexpensive.  The  fire  is 


WELDING  CAST  IRON  143 

applied  to  such  a  casting  by  lighting  a  considerable  quantity  of 
charcoal  in  a  forge  and  placing  it  underneath  the  casting,  being 
sure  to  distribute  it  so  as  to  obtain  a  uniform  increase  in  temper- 
ature. This  is  rather  difficult  and  experience  is  the  only  guide. 
It  is  evident  that  there  is  more  chance  for  a  draft  around  the 
outside  of  the  casting  than  in  the  center,  that  a  heavier  section 
will  require  more  charcoal  than  a  lighter  one,  and  that  in  the 
open  spaces  too  much  charcoal  should  not  be  applied.  In  this 
particular  case  it  was  found  that  too  much  fire  had  been  put 
along  the  part  AB,  Fig.  40,  so  that,  after  the  casting  had  become 
quite  warm,  the  distance  between  the  tram-marks  had  increased 
|  inch.  In  order  to  remove  the  strain  set  up,  the  fire  was  shifted 


Fig.  39.  Heating  Boiler  Casting  showing  Arrangement  for  Preheating 

toward  both  ends,  but  still,  after  the  casting  had  become  red, 
it  was  found  that  after  allowing  for  expansion,  the  tram-marks 
had  separated  -£$  inch,  which  indicated  that  there  was  a  strain 
somewhere  in  the  original  casting. 

When  the  charcoal  was  first  placed  underneath  the  section, 
care  was  taken  not  to  use  too  much,  and  from  time  to  time,  as 
the  casting  became  warm,  it  was  added  in  small  quantities,  but 
more  rapidly  toward  the  latter  part  of  the  heating;  during  this 
time,  the  top  of  the  casting  was  kept  covered  with  asbestos 
paper.  It  is  necessary,  however,  to  punch  holes  in  the  paper 
to  permit  of  sufficient  draft  to  keep  the  charcoal  burning.  The 
paper  tends  to  distribute  the  heat  more  uniformly. 


144  WELDING  CAST   IRON 

The  Welding  Operations.  —  The  first  welding  done  was  to 
weld  the  boss.  On  account  of  the  difficulty  of  reaching  it, 
the  casting  had  to  be  raised  from  the  fire  and  stood  on 
its  end,  so  that  the  work  could  be  done  quickly.  It  was  care- 
fully covered  with  asbestos  paper  while  this  weld  was  being 
made,  then  replaced  in  the  fire  and  allowed  to  come  to  a  uni- 
form temperature.  Then  the  piece  which  had  been  cut  out 
was  put  into  place,  and  the  sides  C  and  D,  Fig.  40,  welded. 
The  casting  was  then  turned  over,  again  allowed  to  come  to 
a  uniform  temperature,  and,  beginning  at  what  was  then  the 
bottom  of  the  welds,  the  V's  were  filled  up  and  the  weld 


Fig.  40.   Heating  Boiler  Casting  ready  for  Preheating  Fire 
to  be  started 

finished  at  the  boss.  During  the  welding  it  was  necessary  to 
pack  the  top  of  the  casting  heavily  with  asbestos,  as  the 
welders  had  to  stand  over  it  to  reach  the  bottom  of  the  ver- 
tical welds.  It  always  pays  to  protect  the  welders  as  much 
as  possible  in  case  of  heavy  fires,  as,  if  this  is  not  done,  they 
cannot  do  good  work. 

Distortion  of  Casting.  —  After  the  weld  was  finished,  it  was 
found  that  the  trammed  distance  had  increased  £  inch.  Inas- 
much as  there  was  no  strain  in  the  casting  after  the  work  was 
done,  as  it  had  been  uniformly  heated  after  welding,  this  J  inch 
represented  the  total  amount  of  strain  in  the  casting.  When 
cold,  a  thorough  hammer  test  with  a  light  sledge  was  made,  as 
well  as  a  pressure  test,  and  everything  was  found  to  be  in  good 


WELDING  CAST  IRON  145 

condition.  It  is  evident  that  this  |-inch  expansion  had  to  be 
taken  care  of,  as  the  push  nipples  could  not  be  put  back  in  place 
if  it  were  not.  The  following  method  of  taking  care  of  it  has 
been  found  in  all  cases  to  be  entirely  satisfactory.  The  push 
nipples  are  made  either  of  cast  iron  or  steel,  and  the  method 
followed  is  to  cut  the  nipple  in  half  with  a  hacksaw.  The  sec- 
tion is  erected  in  place  with  each  half  of  the  push  nipple  in  its 


Fig.  41.  Upright  of  Broken  Press  Frame 

respective  hole.  A  line  is  then  carefully  scribed  with  a  sharp 
point  along  the  exposed  surfaces  where  the  two  halves  offset, 
the  pieces  removed  and  welded  to  suit  their  new  position.  If 
this  is  carefully  done,  it  will  be  found  that  the  result  is  entirely 
satisfactory. 

Repairing  a  Press  Frame.  —  Fig.  46  shows  a  large  press  frame 
which  is  broken.  The  top  of  it  is  very  close  to  the  wooden  roof 
of  the  building.  Inasmuch  as  it  would  have  been  quite  expensive 
to  remove  the  casting,  an  attempt  was  made  to  weld  it  in  place. 
Fig.  41  shows  the  size  and  nature  of  the  breaks,  the  bottom  of 


146  WELDING  CAST  IRON 

one  of  which  was  comparatively  easy  to  reach,  both  to  prepare 
and  weld.  Fig.  42  shows  that  the  top  break  was  prepared  nearly 
through  the  casting  at  the  point  A  from  the  side  shown,  while  at 
B  the  preparation  was  made  equally  on  both  sides.  This  was  done 
in  order  to  save  the  bearing.  It  will  be  noticed  from  Fig.  46 
that  the  bearing  on  the  inside  of  the  broken  side  had  a  large 
projection,  and  nearly  half  of  this  would  have  had  to  be  cut  off 
if  the  bevel  had  been  prepared  evenly  on  both  sides. 


Fig.  42.   Showing  Breaks  through  Metal  5  by  17  and  5  by  14  Inches 

Preheating  and  Welding  the  Frame.  —  The  heating  of  these 
breaks,  particularly  the  upper  one,  was  quite  a  problem,  and 
trouble  was  anticipated  in  controlling  the  contraction,  partly 
because  the  upper  part  of  the  casting  was  much  heavier  than  the 
lower  part,  and  also  because,  as  it  was  very  close  to  the  wooden 
roof,  it  was  feared  that  sufficient  heat  could  not  be  applied  to 
raise  the  casting  to  the  same  temperature  as  below;  that  this 
fear  was  justified  was  proved  by  the  results.  However,  it  was 
determined  to  make  the  attempt,  a  plan  having  been  worked  out 


WELDING  CAST  IRON  147 

whereby,  if  trouble  should  occur,  it  could  be  overcome.  The 
heating  was  done  by  pans  made  of  old  carbide  cans  hung  by 
wire  from  the  upper  part  of  the  casting  and  surrounding  the 
welds.  These  pans  were  located  in  order  to  secure  as  uniform 
an  expansion  as  possible,  and,  while  the  breaks  shown  in  Fig. 
42  were  being  welded,  fire  was  maintained  in  pans  on  the  opposite 
side  in  order  to  avoid  any  irregular  strains  due  to  vertical  con- 
traction. It  was,  however,  not  anticipated  that  any  trouble 


Fig.  43.   Crack  on  Opposite  Upright  prepared  for  Welding 

would  come  from  the  vertical  contraction.  The  difficulty 
feared  was  the  difference  between  the  horizontal  contractions  at 
C  and  Z>,  Fig.  42.  It  is  evident  that  section  C  is  much  lighter 
than  D  and  that,  in  order  to  extend  the  castings  the  same  amount, 
a  much  heavier  fire  would  have  to  be  maintained  at  the  latter 
point  than  at  the  former.  While  the  pans  were  placed  entirely 
across  the  top  at  D,  it  was  found  impossible,  with  as  heavy  a 
fire  as  could  be  kept  up,  to  obtain  the  same  amount  of  expansion 
horizontally,  although  the  width  of  the  fire  was  about  4  inches 


148  WELDING  CAST  IRON 

all  around  the  casting,  except  at  E,  where  the  pan  was  cut  off 
to  allow  the  casting  to  stay  as  cool  as  possible.  In  other  words, 
the  lower  pan  went  no  further  than  the  break,  while  the  upper 
pan  not  only  covered  the  break  but  also  the  opposite  side  of 
the  casting. 

In  spite  of  these  precautions,  and  while  no  new  cracks  appeared 
directly  after  the  welds  were  made,  a  hammer  test  later  devel- 
oped a  crack  at  A,  Fig.  43.  This  was  the  result  anticipated. 


Fig.  44.   Press  Frame  showing  Breaks  prepared  for  Welding  by 
Drilling  and  Chipping 

The  solution  of  the  trouble  was  to  first  cut  the  casting  entirely 
through,  as  at  B,  and  weld  A.  The  crack  at  A  only  extended 
about  4  inches  from  the  inside  corner,  but  the  V  was  made  on 
both  sides  about  i|  inch  deep  at  C,  in  order  to  insure  uniform 
heating  with  the  torch.  It  was  an  easy  matter  to  place  a  pan 
opposite  B  and  one  at  Z),  and  also  two  others  opposite  B  and 
D  on  the  other  side  of  the  frame.  The  desired  expansion  was 
obtained  without  any  trouble,  and  the  casting  welded  at  B; 


WELDING  CAST   IRON  149 

the  tram-marks  showed  that  the  casting  came  back  to  its  original 
position. 

In  Fig.  44  will  be  seen  the  preparation  of  a  small  crack  on  the 
left  upright.  This  gave  no  trouble  in  welding,  as  the  large  body 
of  metal  left  forced  the  expansion  to  take  place  as  was  desired. 
However,  the  precaution  to  heat  the  other  upright  also  was  taken 
while  welding.  The  whole  casting  weighs  about  twelve  tons. 


Fig.  45.   Section  of  Press  Frame  after  Welding 

The  problem  in  this  case  was  to  do  the  welding  without 
removing  the  frame.  There  would  have  been  no  trouble  in 
welding  it  had  it  been  removed,  because  not  only  could  the 
different  parts  of  the  casting  be  brought  to  a  uniform  temper- 
ature, but,  as  the  welding  would  have  been  done  horizontally, 
it  would  have  been  much  easier.  As  it  was,  all  the  metal  had  to 
be  added  on  the  side.  The  two  main  breaks  required  four  welders 
for  a  period  of  twenty-two  hours,  as  the  heat  was  very  great, 
due  to  the  low  roof,  which  it  was  necessary  to  protect  from  dam- 
age by  fire,  and  also  due  to  the  fact  that  the  space  between  the 


150  WELDING  CAST  IRON 

uprights  was  only  about  three  feet,  so  that  part  of  the  time  the 
men  were  working  between  the  pans  on  the  upright. 

There  was  a  shrinkage  strain  in  the  original  casting;  this 
made  it  necessary  to  rebore  the  bearings.  It  was  realized 
before  the  job  was  started  that  this  would  have  to  be  done. 
This  frame  has  been  in  service  for  over  a  year  since  welding, 
and  has  been  subjected  to  heavier  work  than  ever  before,  with 
entirely  satisfactory  results. 

Difficulties  with  Cast-iron  Welds.  —  A  difficulty  that  is  en- 
countered in  certain  cases,  particularly  in  cast  iron,  is  the  for- 
mation of  blow-holes  extending  from  some  distance  down  in  the 
weld  to  the  surface.  These  are  generally  small  and  in  the  major- 
ity of  cases  not  important.  However,  in  gas-engine  cylinder 
water  jackets  or  similar  places,  where  leaks  are  objectionable, 
they  should  be  avoided,  and  in  all  cases  care  should  be  taken  to 
remove  them  during  welding.  They  are  caused  by  small  par- 
ticles of  slag  or  dirt,  which  contain  in  them  a  certain  amount 
of  air  or  gas.  They  can  generally  be  noticed  by  their  intensely 
white  color.  They  are  probably  composed  of  silica  which  will 
not  melt.  All  that  needs  to  be  done  is  to  melt  the  metal  around 
them  and  allow  them  to  float  to  the  surface,  removing  them  either 
with  the  welding-rod  or  by  the  use  of  scaling  powder.  A  similar 
condition  is  sometimes  noticed  in  a  piece  that  has  not  been 
heated  sufficiently;  here  the  remedy  is  obvious. 

Hard  Spots.  —  There  is  one  condition  that  exists  frequently 
in  cast-iron  welds  which  has  caused  a  great  deal  of  trouble  and 
rather  adverse  comment,  and  that  is  "hard  spots."  If  good 
welding-rods  are  used,  the  spots  are  the  result  of  carelessness  in 
welding,  and  generally  occur  at  the  points  where  the  old  and  new 
metal  join.  It  is  very  easy  to  avoid  them  by  making  the  new 
metal  at  the  edge  of  the  weld  a  little  higher  than  the  surface  of 
the  old  metal,  and  then  melting  the  old  metal  and  new  metal, 
allowing  the  new  to  run  into  the  old.  If  this  is  properly  done, 
there  will  be  no  hard  spots  at  that  point.  It  is  a  mistake  to  say 
that  scaling  powder  produces  hard  spots.  Certain  kinds  may 
make  a  very  thin  hard  film  on  the  weld,  but  the  hard  spot  which 
gives  trouble  is  the  one  first  referred  to.  Of  course,  in  some  cases 


WELDING  CAST  IRON 


Fig.  46.   View  showing  Both  Sides  of  Press  Frame  after  welding 
is  completed  and  Bearings  have  been  repaired 

where  no  finishing  is  to  be  done  except  by  grinding,  it  is  not 
worth  while  to  bother  about  hard  spots,  but  where  any  machining 
or  filing  is  necessary,  they  should  be  avoided.  The  real  cause 
of  such  hard  spots  is  as  follows: 


152  WELDING  CAST  IRON 

It  will  be  noticed  that  they  generally  occur  in  comparatively 
thin  sections,  or,  if  in  thicker  sections,  where  the  metal  has  not 
been  thoroughly  heated;  also  that  they  generally  are  more 
frequent  in  fine-grained  iron  than  in  coarser  metal.  The  presence 
of  silicon,  manganese,  and  sulphur  in  iron  in  certain  proportions 
produces  a  metal  that  will  readily  chill  when  heated  and  allowed 
to  cool  rapidly.  The  presence  of  large  amounts  of  the  elements 
favorable  to  producing  soft  iron  will  not,  under  extremely  rapid 
cooling,  make  the  iron  soft.  Now  in  thin  sections,  air  cooling 
and  the  .conduction  of  the  heat  away  by  the  colder  surrounding 
metal  are  sufficiently  rapid,  with  the  proper  chemical  composition, 
to  produce  chilled  iron,  and  it  is  surprising  how  heavy  the  sec- 
tion may  be  and  still  chill  when  cooled  in  the  air.  If  allowed 
to  cool  in  the  fire,  the  cooling  will  be  much  slower  and  there  will 
be  less  danger  of  hard  spots.  The  action  is  really  the  formation 
of  chilled  iron,  and  from  such  tests  as  the  author  has  made,  the 
chilling  does  not  take  place  in  the  added  metal,  but  occurs 
entirely  in  the  original  material.  This  is  on  account  of  the  high 
amount  of  silicon  in  the  welding-rod,  which  is  favorable  to  the 
production  of  soft  iron. 

Malleable  iron,  when  heated  beyond  a  certain  point,  will  revert 
to  its  original  state  of  white  or  chilled  cast  iron  with  consequent 
hardness.  Care  should  be  taken  not  to  heat  the  metal  any  more 
than  is  absolutely  necessary.  There  is  no  other  metal  that  gives 
any  trouble  from  hard  spots. 

Chilling  Effect  of  Welding  Table.  —  Very  often  the  welding  is 
performed  on  a  metal  table,  in  order  to  facilitate  alignment  of 
the  broken  pieces.  If  the  casting  to  be  welded  is  a  flat  section, 
a  very  natural  thing  for  the  welder  to  do  is  to  lay  it  on  the  welding 
table  and,  by  simply  butting  the  edges  of  the  break  together, 
alignment  is  secured  and  the  weld  made.  No  thought  is  given 
to  the  conduction  of  heat  from  the  weld  by  the  cold  table  sur- 
face, with  the  result  that  the  heat  is  carried  away  from  the  weld 
and  at  least  the  bottom  part  of  the  weld  is  chilled  and  made 
hard.  A  casting  welded  under  these  conditions  may  be  warped. 
If  it  is  essential  for  a  weld  to  be  made  under  these  conditions, 
use  asbestos  paper  or  firebrick  to  prevent  the  conduction  of  heat; 


WELDING   CAST   IRON  153 

but,  when  possible,  make  the  weld  in  a  forge,  or  use  a  charcoal 
fire,  a  gas  torch,  or  an  oil  torch,  both  to  preheat  and  to  effect 
slow  cooling.  The  safe  and  economical  way  is  to  use  one  of  these 
agencies  to  bring  the  line  of  welding  up  to  the  red  heat,  make 
the  weld,  then  use  the  same  agency  to  again  bring  the  work 
slowly  back  to  a  red  heat,  and  cover  it  with  a  good  nonconductor, 
such  as  asbestos,  mica,  or  ashes. 

Distortion .  in  Welding  Cylinders.  —  Another  difficulty  that 
quite  frequently  arises  is  the  claim  made  by  a  customer  that  the 


Fig.  47.  Foot-treadle  illustrating  Difficulties  in  Welding 

piece  has  been  distorted  by  welding;  for  instance,  an  automobile 
cylinder  in  which  the  bore  is  claimed  to  have  been  warped  by 
heating.  This  does  occur  at  times,  but  only  in  cases  of  very 
bad  breaks,  in  the  case  of  a  certain  type  of  cylinders  where  the 
connections  between  the  cylinder  barrel  and  jacket  are  so  rigid 
that  it  requires  a  red  heat  to  make  the  weld,  or  where  the  cylinder 
is  carelessly  overheated.  There  is  also  a  number  of  old-style 
cylinders  which  were  not  annealed  after  rough-boring,  and  which 
warp  out  of  shape  even  with  the  moderate  heat  required  for  jacket 
welding.  The  author,  in  the  beginning  of  his  work,  measured 
with  a  micrometer  caliper  the  diameters  at  both  the  top  and 
bottom  of  a  large  number  of  cylinders,  and,  with  the  exceptions 


154  WELDING  CAST  IRON 

above  noted,  he  has  yet  to  find  any  noticeable  distortion  of 
cylinders  of  automobile  motors  or  gas  engines.  Of  course,  there 
is  always  some  difference  in  diameters  of  such  cylinders  after 
a  period  of  service,  due  to  natural  wear.  This  is  sometimes 
excessive,  and  will  be  readily  detected  by  proper  measurements 
before  welding. 

The  following  case,  while  not  of  this  type  of  cylinder,  illus- 
trates the  point  very  well.  A  Corliss  engine,  16  inches  in  diam- 
eter by  36  inches  stroke,  burst  out  the  top  of  the  steam  chest 
by  freezing,  due  to  the  man  in  charge  not  draining  it  during 
cold  weather.  The  cylinder  was  calipered  at  three  points  and 


Fig.  48.   Crankcase  in  which  Shrinkage  Strains  had  to  be  overcome  in  Welding 

gages  made  to  suit,  a  maximum  difference  being  found  of  0.012 
inch,  due  to  wear.  After  welding  and  cooling,  the  latter  requir- 
ing two  days,  it  was  found  that  the  maximum  change  of  di- 
mensions of  the  bore  was  less  than  0.003  inch,  not  enough  to 
cause  any  trouble.  The  claim  of  the  customer  that  the  cylinder 
had  been  distorted  was,  therefore,  readily  disproved.  It  is 
easy  to  see,  however,  that  if  the  precaution  of  measuring  before 
welding  had  not  been  taken,  it  would  have  been  very  difficult, 
if  not  impossible,  to  convince  the  customer  that  the  welding 
operation  had  not  injured  his  cylinder.  Therefore,  it  is  ad- 
visable, in  the  case  of  any  job  about  which  a  question  is  likely 
to  be  raised,  that  careful  measurements  be  taken,  the  ac- 
curacy depending  upon  conditions,  and  a  record  kept  for  future 
reference, 


WELDING   CAST   IRON  155 

Expansion  and  Contraction.  —  One  of  the  greatest  difficulties 
to  be  contended  with  is  the  control  of  expansion  and  contraction 
due  to  differences  in  temperature  of  different  parts  of  the  piece 
welded.  Cast  iron,  being  comparatively  brittle,  is  peculiarly 
subject  to  cracks  caused  by  temperature  strains,  but  all  other 
metals  have  also  such  strains  in  them,  and,  while  they  may  not 


Fig.  49.   Duplex  Pump  Base  showing  Method  of  Lining  up 
Bearings  and  Saving  Babbitt 

crack,  they  change  their  shape,  if  care  is  not  taken  to  handle  them 
properly.  There  is  no  general  rule  for  taking  care  of  expansion 
and  contraction  strains.  It  must  be  remembered  that  they 
are  always  present,  and  experience  will  show  in  what  way  they 
will  manifest  themselves.  Sometimes  they  can  be  avoided  by 
setting  the  pieces  so  as  to  allow  the  shrinkage  to  bring  the  parts 
to  their  original  shape,  but  considerable  thought  and  ingenuity 


156  WELDING  CAST  IRON 

has  to  be  exercised  at  times  to  take  care  of  it.  Sometimes  a 
sound  weld  can  be  made,  but  the  strains  will  have  been  distrib- 
uted through  the  piece,  distorting  it  and  requiring  the  addition 
of  extra  metal  to  some  of  the  finished  surfaces  so  that  they  may  be 
machined  to  their  original  dimensions. 

Practical  Examples  of  Neutralizing  Contraction  Stresses. — 
Fig.  47  is  introduced  to  show  the  principle  of  taking  care  of 


Fig.  50.   Duplex  Pump  Base  showing  Finished  Weld 

contraction.  It  will  be  noticed  that  this  piece  has  been  welded 
before  and  that  it  did  not  break  in  the  weld.  It  really  is  not 
strong  enough  for  the  work  to  which  it  is  subjected.  Before 
taking  the  photograph,  the  crack  was  wedged  apart  to  show 
it  more  distinctly.  If  breaks  A  and  B  are  welded  at  different 
times,  it  will  be  hard  to  avoid  shrinkage  strains,  as  the  distance 


WELDING  CAST  IRON 


157 


between  the  two  welds  is  very  short,  not  over  3  inches.  If, 
however,  they  can  be  welded  at  the  same  time,  this  difficulty 
will  be  overcome,  as  the  shrinkage  will  be  uniform.  If  the  crack 
is  opened  to  allow  for  contraction,  the  edges  of  the  crack  will 
not  separate  parallel  to  each  other,  but  will  swing  around  the 


Fig.  51.  Pump  Body  showing  Method  of  Saving  Babbitted  Bearings 

point  C  as  a  center,  causing  strain  at  that  point.  The  method 
followed,  therefore,  was  to  heat  the  bar  D  with  a  gas  flame  suffi- 
ciently to  open  the  crack  the  desired  amount.  Two  welders, 
one  working  on  each  crack,  finished  the  welds  at  the  same  tune. 
A  heavier  tip  was  used  on  crack  B  than  on  crack  A ,  as  the  section 
was  heavier  and  larger.  It  might  be  stated  that  the  old  welds 


158 


WELDING  CAST  IRON 


shown  were  made  over  a  year  before  the  piece  broke  the  second 
time. 

Fig.  48  is  shown  to  indicate  one  method  of  partly  overcoming 
shrinkage  strains  that  would  ordinarily  occur.  The  break  does 
not  extend  to  the  bottom  flange  of  the  crankcase.  The  part 
broken  out  was  in  four  small  pieces  when  received,  and,  in 
welding  them  in,  the  edges  were  welded  first,  leaving  the  section 
B  about  iV  inch  higher  than  its  original  location.  Before  weld- 
ing, a  little  metal  was  added  to  the  edges  of  the  holes  A  in  the 


Fig.  52.  Crankcase  in  which  End  Bearing  is  broken  off 

piece,  to  provide  for  the  elevation  above  described,  so  that  the 
holes  could  be  finished  to  their  original  size.  The  bridge  between 
the  holes  was  welded  first,  then  the  sides,  and  after  that  the  cen- 
ter. While  this  will  not  entirely  remove  the  shrinkage  strains,  it 
gives  a  certain  opportunity  for  shrinkage  to  occur  without  caus- 
ing trouble.  In  this  instance,  the  metal  was  of  good  quality  and 
no  trouble  whatever  was  experienced.  This  method  can  also  be 
followed  at  times  in  welding  badly  frozen  cylinder  water  jackets. 
Saving  Babbitt  Bearings  when  Welding. —  A  method  used 
for  saving  the  babbitt  bearings,  and  also  for  the  purpose  of  lining 
up  the  bearing  that  was  broken  off  as  shown  in  Fig.  50,  is  indicated 


WELDING  CAST  IRON  159 

in  Fig.  49.  A  piece  of  3-inch  seamless  tubing  was  clamped  in 
the  bottom  bearing,  using  a  piece  of  asbestos  paper  E  to  raise 
it  slightly  above  its  original  position  to  allow  for  shrinkage. 
Additional  allowance  was  made  by  raising  the  bearing  A  about 
sV  inch  vertically  above  the  proper  position.  The  bottom  of 
the  tube  was  plugged  with  wet  asbestos,  and  it  was  then  filled 
with  water.  Asbestos,  as  shown  at  D,  was  packed  around  the 
bearing  and  the  fire  built  as  usual,  the  sheet  of  tin  H  being 
placed  to  locate  the  bottom  of  the  fire.  The  bricks  below  the 


Fig.  53.   Same  Crankcase  as  shown  in  Fig.  52  with  End  Bearing  and  Mandrel 

in  Place 

tin  are  simply  for  the  purpose  of  supporting  the  fire.  The  bricks 
above  the  tin  surround  the  fire  and  confine  it  to  the  desired  loca- 
tion. The  break  was  at  C  and  is  more  clearly  shown  in  Fig.  50 
which  shows  the  finished  job.  The  metal  was  i  J  inch  thick  and 
the  break  12  inches  long.  When  tested  after  cooling,  it  was 
found  that  the  bearing  was  in  alignment  within  the  thickness 
of  a  piece  of  paper,  or  about  0.003  inch.  A  slight  scraping  was 
all  that  was  necessary  to  take  care  of  this. 

Fig.  51  shows  one  method  of  preserving  babbitt  bearings  in 
cases  where  the  part  is  to  be  heated  to  a  high  temperature.    The 


i6o 


WELDING   CAST   IRON 


break  in  this  case  was  on  the  bottom  of  the  pump  body.  It  is 
evident  that  this  had  to  be  heated  quite  hot  in  order  to  com- 
pensate for  shrinkage.  This  was  done  in  a  furnace  built  of  fire- 
brick, the  bearings  being  covered  at  A,  B,  C,  and  D  with  wet 


Fig.  54.  Eighty-five-ton  Press,  showing  where  Crack  was  repaired 
in  Main  Frame 

asbestos,  and  the  channels  at  E  and  F  plugged  with  asbestos  to 
keep  the  water  in  them  from  running  back  into  the  fire.  These 
precautions,  together  with  keeping  the  asbestos  constantly  wet 
and  the  channels  filled  with  water,  answered  the  purpose  admi- 
rably and  the  bearings  were  not  damaged. 


WELDING  CAST  IRON  161 

Providing  for  Proper  Alignment.  —  Figs.  52  and  53  show  a 
method  that  can  be  frequently  employed  to  replace  a  bearing 
so  that  it  is  very  nearly,  if  not  absolutely,  in  its  original  position. 
In  Fig.  52  two  pieces  of  cardboard,  each  about  0.015  inch  thick, 
have  been  placed  in  the  two  sound  bearings.  The  broken-out 
end  bearing  A  is  then  put  in  place  without  the  use  of  any  card- 
board, a  mandrel  being  held  in  bearings  A  and  C.  Bearing 
A  is  held  against  the  mandrel  by  means  of  clamps  and  the  nuts 
of  the  bearing  cap  studs.  This  raises  the  bearing  A  slightly 
above  its  original  position,  and  compensates  for  the  shrinkage 
of  the  weld,  and  in  this  particular  case  no  finishing  was  needed 
except  a  little  scraping  of  bearing  A.  The  three  bearings  in 
this  instance  are  of  different  sizes.  It  should  also  be  stated 
that  cold-rolled  steel,  while  it  is  quite  heavy,  is,  as  a  general  rule, 
cheaper  for  mandrels  than  tubing.  Of  course,  if  many  crank- 
cases  of  one  kind  are  to  be  taken  care  of,  it  will  be  better  to  use 
tubing,  but  this  material  is  expensive  and,  for  ordinary  purposes, 
unnecessary. 

Punch  Press  Repair.  —  Fig.  54  shows  a  repair  made  in  a  large 
punch  press,  the  capacity  of  which  is  eighty-five  tons.  This 
press  developed  a  crack  in  the  main  frame  shortly  after  it  was 
purchased,  as  indicated  by  the  white  line  in  the  illustration. 
A  new  frame  would  have  cost  about  $700.  It  was  repaired  by 
the  oxy-acetylene  welding  process  for  approximately  $150.  In 
repairing,  it  was  necessary  to  dismantle  the  entire  machine,  lay 
it  on  its  side,  and  cut  away  most  of  the  frame  at  an  angle  of 
approximately  45  degrees  in  the  crack.  The  part  was  heated 
by  two  blow  torches  to  a  bright  red.  Then  the  process  of  build- 
ing it  up  with  the  oxy-acetylene  flame  proceeded,  the  time  re- 
quired being  about  twenty  hours  of  continuous  work.  After  the 
job  had  cooled,  the  press  was  put  back  on  its  foundation  and  the 
main  shaft,  which  passes  through  four  solid  bearings  in  the  main 
frame,  was  found  to  fit  perfectly.  Every  part  went  back  into 
place  without  the  slightest  indication  of  binding.  The  frame 
of  this  press  is  stronger  to-day  than  a  new  one  would  have  been, 
because  the  weak  part  is  built  up  and  is  thus  reinforced. 


CHAPTER  VI 

WELDING    STEEL,    MALLEABLE    IRON,    COPPER,    AND 
COPPER    ALLOYS 

THE  melting  point  of  ordinary  machine  steel  is  about  2650 
degrees  F.,  that  of  wrought  iron  about  2740  degrees  F.,  while 
that  of  cast  iron  varies,  depending  upon  the  composition,  from 
2000  to  2 200  degrees  F.  Hence,  the  welding  of  wrought  iron  and 
steel  presents  a  problem  entirely  different  from  that  involved 
in  the  welding  of  cast  iron.  Steel  less  than  f  inch  thick  can  be 
welded  without  the  addition  of  any  metal.  If  the  thickness 
exceeds  |  inch,  the  edges  should  be  beveled  or  chamfered.  It  is 
very  important  not  to  add  any  welding  material  until  the  edges 
are  fused  or  molten  at  the  place  where  the  weld  is  being  made. 
The  welding  metal  should  be  of  special  wire,  and  in  no  case 
should  the  flame  be  held  at  one  point  until  a  foam  is  produced,  as 
this  is  an  indication  that  the  metal  is  being  burned. 

General  Procedure  in  Steel  Welding.  —  The  flame  should  not 
be  held  steadily  in  the  center  of  the  weld,  but  should  be  given 
a  circular  motion  with  an  uplifting  movement  at  each  revolution, 
the  object  being  to  drive  the  molten  metal  toward  the  center  of 
the  weld.  An  excess  either  of  oxygen  or  acetylene  is  dangerous 
in  welding  steel,  and  care  should  be  taken  to  keep  the  flame 
neutral  at  all  times. 

Metallurgy  of  Iron  and  Its  Relation  to  Welding.  —  Iron  is 
one  of  the  chemical  elements,  existing  in  large  quantities  in 
nature  in  the  form  of  ores.  These  ores  are  reduced  by  various 
processes  and  from  them  is  produced,  first,  pig  iron.  In  the  pro- 
duction of  ordinary  castings,  the  pig  iron  is  remelted  and  mixed 
with  scrap  castings  and  other  materials,  to  produce  what  the 
foundryman  desires.  The  metal,  however,  retains  all  the  char- 
acteristics of  pig  iron,  except  that  its  constituents  vary  in  quan- 
tity. All  cast  iron  consists  of  pure  iron  mixed  with  different 

162 


WELDING   STEEL  163 

proportions  of  carbon,  silicon,  manganese,  sulphur,  and  phos- 
phorus. There  are  other  elements,  but  they  exist  in  such  small 
amounts  and  have  such  a  slight  effect  on  the  quality  of  the  metal 
that  they  need  not  be  considered  here.  The  effect  of  these 
five  elements  on  the  quality  of  cast  iron  depends  upon  their  rela- 
tive proportions;  and  while  much  is  known  in  this  connection, 
there  is  still  much  to  learn,  as  their  influences  are  complicated, 
not  only  by  their  effects  on  the  iron,  but  upon  each  other.  The 
element  that  has,  by  far,  the  greatest  effect  on  iron,  is  carbon; 
in  fact,  it  has  more  effect  than  all  the  others  together;  and  as 
the  others  are  present  in  comparatively  small  amounts  in  good 
iron  or  steel,  they  will  be  considered  only  incidentally. 

Influence  of  Carbon.  —  Carbon  exists  in  pig  iron,  or  ordinary 
cast  iron,  in  two  conditions,  which  are  called  "combined"  carbon, 
and  "free"  or  "graphitic"  carbon.  The  combined  carbon  exists 
as  carbide  of  iron,  or,  in  other  words,  it  is  alloyed  with  the 
iron,  forming  a  definite  chemical  compound.  Graphitic  carbon 
exists  in  the  free  state  as  graphite,  and  can  be  noticed  in  very 
soft  pig  iron  as  it  will  blacken  the  fingers  or  make  a  mark  on  white 
paper.  Cast  iron  contains  a  total  amount  of  carbon  varying 
from  about  2^  to  4^  per  cent.  The  percentage  of  graphitic 
carbon  in  a  cast  iron  having  a  given  total  amount  of  carbon, 
varies  in  accordance  with  the  size  of  the  casting  and  the  rapidity 
with  which  it  is  cooled.  Slow  cooling  of  a  large  casting  increases 
the  percentage  of  graphitic  carbon,  while  the  total  amount  of 
carbon  remains  the  same.  This  graphitic  carbon  exists  in  the 
iron  in  the  shape  of  plates  between  the  grains,  and  it  is  evident 
that  the  larger  these  plates  are,  the  weaker  the  iron.  It  is  well 
known  that  large  castings  have  less  tensile  strength  per  square 
inch  than  small  castings  poured  from  the  same  ladle. 

White  Iron.  —  There  is  a  variety  of  cast  iron  known  as 
"white"  iron  which  contains  no  graphitic  carbon.  It  is  some- 
times called  "chilled"  iron,  because  when  iron  of  proper  chem- 
ical composition  is  cast  against  a  steel  or  iron  chill  plate,  or  other 
cold  surface,  it  cools  quickly  and  the  quality  of  intense  hardness 
which  is  desirable  in  certain  castings  is  obtained.  It  is  called 
white  iron  on  account  of  its  silvery  appearance  when  broken. 


164  WELDING   STEEL 

Iron  suitable  for  chilling  has  a  smaller  percentage  of  silicon  and 
a  larger  percentage  of  manganese  than  ordinary  cast  iron,  be- 
cause silicon  has  the  property  of  preventing  carbon  from  com- 
bining with  iron,  while  manganese  has  exactly  the  opposite 
effect.  This  is  the  reason  why  ordinary  cast  iron  is  unsuitable 
for  welding-rods.  Ordinary  castings  do  not  require  a  high  per- 
centage of  silicon,  and  a  reasonable  amount  of  manganese  is  not 
objectionable,  but  is  of  some  advantage  at  times  in  making  the 
iron  close-grained  and  strong  and  in  counteracting  the  bad 
effects  of  sulphur.  Therefore,  welding-rods  are  made  from  iron 
which  is  high  in  silicon  and  low  in  manganese,  so  that  the  metal 
in  the  weld  may  be  soft  and  readily  machined. 

Crystalline  Structure  of  Iron  and  Steel.  —  On  account  of  the 
size  of  the  grains  in  a  cast-iron  fracture,  it  is  well  known  to  every- 
one handling  it  that  it  is  crystalline.  A  magnifying  glass  will 
readily  disclose  this  fact.  It  is  not,  however,  so  well  known 
that  steel  is  equally  as  crystalline  as  cast  iron;  for  instance,  a 
piece  of  hardened  tool  steel  does  not  appear  to  be  crystalline, 
and,  in  the  case  of  some  high-speed  steels,  the  fracture  appears 
almost  amorphous.  It  is  very  common  to  hear  the  expression, 
"That  piece  of  steel  broke  because  it  was  crystallized."  It  is 
still  less  commonly  known,  and  indeed  many  metal  workers  do 
not  believe,  that  wrought  iron  is  of  crystalline  structure,  but  it 
is  a  fact.  This  is  very  readily  seen  by  a  comparatively  low 
power  magnification  under  a  microscope,  of  a  properly  prepared 
specimen.  Every  blacksmith  knows  that  a  piece  of  wrought 
iron  nicked  and  broken  across  the  anvil  will  show  a  more  or  less 
crystalline  fracture,  although  it  is  frequently  attributed  to 
defective  material  or  sudden  shock,  or  some  other  more  or  less 
obscure  cause. 

Difference  between  Cast  Iron,  Wrought  Iron,  and  Steel.  - 
The  essential  difference  between  cast  iron,  wrought  iron,  and 
steel  is  the  percentage  of  carbon  contained  in  them.  As  before 
stated,  cast  iron  varies  from  i\  to  4^  per  cent,  while  steel  contains 
from  0.05  to  2  per  cent,  wrought  iron  containing  0.05  per  cent, 
or  less.  The  essential  difference  between  steel  and  wrought 
iron,  using  the  terms  in  their  commercial  sense,  is  simply  in  the 


WELDING   STEEL  165 

method  of  manufacture.  Wrought  iron  is  made  by  puddling 
cast  iron  in  a  reverberatory  furnace  until  the  carbon  is  burned 
out  of  it.  The  resulting  pasty  mass,  which  is  full  of  slag,  is  then 
squeezed  in  a  heavy  press,  which  forces  the  slag  out  of  it,  as  it 
is  more  liquid  than  the  iron.  It  is  then  reheated,  passed  through 
sets  of  rolls,  and,  if  a  better  quality  is  desired,  cut  in  short 
lengths,  piled  together,  heated,  and  again  rolled.  However,  it 
is  impossible  by  this  process  to  remove  all  the  slag,  and  this 
can  be  detected  with  a  magnifying  glass,  and  is  frequently  seen 
by  the  naked  eye  in  a  bar  of  wrought  iron.  This  slag  tends  to 
weaken  the  iron,  not  only  because  it  has  no  tensile  strength 
itself,  but  because  it  prevents  the  grains  from  coming  into 
intimate  contact. 

Steel  is  produced  by  melting  cast  iron,  either  in  a  Bessemer  or 
open-hearth  furnace  for  ordinary  material,  or,  in  the  case  of 
high-quality  materials  for  tools,  etc.,  in  crucibles.  A  Bessemer 
furnace  operates  by  burning  out  the  carbon  entirely,  leaving  a 
mass  of  melted  iron.  The  necessary  amount  of  carbon  is  added 
by  the  use  of  ferromanganese  or  other  high-carbon  material,  and 
the  steel  poured  into  ingots  which  are  rolled  down  to  the  various 
shapes  and  sizes  desired.  The  open-hearth  furnace  is  different 
from  the  Bessemer  in  that  there  is  no  air  blast  used  to  burn  out 
the  carbon  and  that  a  better  mixture  can  be  obtained,  because 
the  process  is  slower  and  under  better  control.  It  produces  a 
better  and  more  uniform  grade  of  steel  than  the  Bessemer  fur- 
nace, and  is  universally  used  at  the  present  time  where  the  best 
quality  is  desired.  It  is  evident  that  the  melting  process  elimi-- 
nates  nearly  all  possibility  of  slag  in  the  metal.  Slag  is  lighter 
than  melted  iron  and  'tends  to  rise  to  the  surface  of  the  liquid 
mass,  while  in  the  puddling  process  the  stirring  up  of  the  pasty 
iron  allows  some  slag  to  be  mixed  in  the  metal  from  which  it 
cannot  later  escape. 

A  crucible  is,  in  reality,  a  small  open-hearth  furnace,  and  its 
use,  as  has  been  stated,  is  confined  to  tool  steel,  which  requires 
careful  control  of  the  carbon  and  other  elements  in  it,  small 
quantities  of  which  materially  affect  the  composition  and  action, 
in  service.  It  is  also  necessary  to  have  great  uniformity  in  the 


1 66  WELDING   STEEL 

product  which  can  be  best  obtained  by  handling  small  quantities 
of  it  at  a  time. 

Kinds  of  Steel  Generally  Welded. —  The  steels  which  the 
welder  will  meet  most  frequently  contain  from  0.20  to  0.45 
per  cent  of  carbon,  and  are  called  " low-carbon"  steels.  They 
do  not  have  any  elements  in  them,  such  as  chromium,  vanadium, 
tungsten,  nickel,  etc.,  which  have  in  the  last  few  years  been 
alloyed  with  ordinary  steel  to  obtain  very  high  tensile  strength 
and  elastic  limit,  and  which  are  mostly  used  in  automobile  con- 
struction so  as  to  obtain  maximum  strength  and  service  with 
the  least  possible  weight. 

The  carbon  in  ordinary  carbon  steels  varies  with  the  uses 
to  which  they  are  put.  For  instance,  boiler  sheets  will  run 
about  o.i  8  per  cent,  spring  steel  about  i  per  cent,  steel  for  rail- 
road axles  about  0.40  per  cent.  There  are  many  varieties  of 
steel  having  carbon  between  these  points;  it  will  be  found  in 
practice  that  the  steels  with  the  least  carbon  weld  most  easily 
and  give  the  best  results.  The  reason  for  this  is  that  when 
steel  is  melted,  as  in  the  welding  process,  the  carbon  is  removed 
from  it  to  a  greater  or  less  degree,  and,  unless  care  is  taken, 
the  steel  will  be  burnt.  The  greater  the  amount  of  carbon,  the 
greater  is  the  danger.  Steel  may  be  overheated  without  burn- 
ing, but,  if  it  is  once  burnt,  it  cannot  be  restored,  except  by 
remelting  it. 

Burning  of  Steel.  —  Some  explanation  in  regard  to  the  burning 
of  steel  may  be  of  assistance  in  making  clearer  some  things  that 
the  welder  will  encounter,  and  help  him  to  avoid  trouble.  As 
stated,  steel  is  composed  of  crystalline  grains,  which  are  smaller 
or  larger  according  to  the  details  of  the  process  of  manufacture. 
These  grains  are  separated  from  each  other  by  thin  membranes 
which  vary  in  composition,  thickness,  and  nature,  depending 
upon  the  percentage  of  carbon,  and  the  heat-treatment  and  work- 
ing to  which  the  steel  has  been  subjected.  During  the  process  of 
melting  steel  with  the  torch,  the  metal  is  subjected  to  a  very 
high  temperature.  If  at  this  high  temperature  the  steel  is  left 
in  contact  with  the  heat  long  enough,  atmospheric  oxygen  finds 
its  way  between  the  grains  and  combines  with  some  of  the  carbon, 


WELDING   STEEL  167 

forming  carbon  monoxide,  forcing  the  grains  apart,  and  making 
the  metal  weak  and  brittle.  This  action  is  intensified  by  the 
film  of  oxide  formed  by  the  action  of  the  oxygen.  This  makes 
it  impossible  to  restore  the  steel  by  heating  to  a  lower  point  and 
forging  it,  as  the  grains  will  not  again  cohere.  In  other  words, 
burning  is  a  mechanical  separation  of  the  crystalline  grains. 

The  welding-rod  ordinarily  used  for  welding  steel  contains 
very  little  carbon,  being  generally  made  of  Swedish  iron.     In- 


Fig.  1.   Welding  together  the  Parts  of  a  Drawn  Steel  Retort.     The 
Operator  feeds  the  Joint  with  a  Special  Grade  of  Iron  Wire 

asmuch  as  the  less  the  carbon  the  less  the  chance  of  burning, 
the  metal  added  in  welding  is  not  burnt,  if  ordinary  care  is  used; 
but,  if  the  parts  welded  are  of  high-carbon  steel,  the  metal  next 
to  the  weld  is  damaged,  with  the  result  that,  while  the  weld 
itself  remains  intact,  the  piece  breaks  next  to  the  weld.  It  is 
impossible  to  burn  wrought  iron,  as  it  has  practically  no  carbon. 
Another  thing  that  should  be  realized  is  that  while  wrought  iron, 
which  has  practically  no  carbon,  melts  at  about  2750  degrees  F., 
the  melting  temperature  of  steel  decreases  as  the  percentage 


i6S  WELDING  STEEL 

of  carbon  increases,  and  steel  with  i|  per  cent  of  carbon  melts 
at  about  2300  degrees  F.  Not  only  is  this  true,  but  it  is  also 
a  fact  that  the  more  carbon  the  steel  contains,  the  longer  time 
it  takes  to  solidify  after  melting,  the  same  as  cast  iron  does,  while 
wrought  iron  solidifies  almost  instantly.  These  two  things,  the 
lowering  of  the  melting  point  and  the  length  of  time  the  metal 
stays  melted,  make  high-carbon  steel  particularly  susceptible 
to  burning.  It  is,  therefore,  practically  impossible  to  weld 
high-carbon  steel,  at  least  steel  containing  over  i  per  cent  of 
carbon,  and  the  larger  the  section,  the  more  difficult  the  work  is, 
as  it  has  to  be  kept  under  the  influence  of  a  high  temperature  for 
a  longer  time. 

What  has  been  said  does  not  refer  to  steel  that  has  simply 
been  overheated.  This  condition  is  brought  about  by  heating 
to  a  very  high  temperature,  but  not  above  the  beginning  of  the 
melting  range  of  temperature.  Such  steel  can  be  restored,  at 
least  to  a  certain  degree,  by  heat-treatment,  and  will  also  be 
helped  by  forging,  if  this  is  possible.  It  is  frequently  claimed 
that  burnt  steel  can  be  restored  by  the  use  of  a  flux  or  by  vari- 
ous methods  of  treatment.  It  is  evident  from  the  explanation 
given  that  this  is  not  possible,  and  that  where  so-called  " burnt" 
steel  has  been  restored,  it  has  not  really  been  burnt,  but  simply 
overheated. 

Methods  for  Welding  Steel.  —  The  methods  used  in  welding 
steel  are  somewhat  different  from  those  followed  in  the  case  of  cast 
iron.  The  ordinary  steels  handled  by  the  welder  solidify  quickly; 
there  is,  therefore,  a  greater  danger  of  the  metal  not  being 
thoroughly  united  at  all  points,  resulting  in  cold-shuts.  The  weld- 
ing-wire is  more  likely  to  be  burnt  on  account  of  its  compara- 
tively small  section.  Therefore,  it  is  necessary  that  the  method 
of  handling  the  torch  and  welding-rod  suit  these  conditions. 

It  is  possible  in  the  case  of  cast  iron  at  times  to  use  a  V  with 
an  angle  of  less  than  90  degrees;  in  fact,  it  is  sometimes  advis- 
able to  do  so.  In  the  case  of  steel,  however,  unless  it  is  less  than 
f  inch  thick,  the  go-degree  angle  must  be  maintained,  or  the 
bottom  of  the  weld  will  not  be  sound  or  will  consist  of  a  series 
of  cold-shuts  and  laps.  Again,  if  the  torch  is  used  to  widen  the 


WELDING  STEEL  169 

V,  a  series  of  " craters"  is  likely  to  be  formed,  which  are  ex- 
ceedingly difficult  to  eliminate.  These  craters  are  caused  by 
the  metal  in  the  center  being  colder  than  the  metal  around  the 
edges,  due  to  the  conduction  of  the  heat  away  from  the  bottom 
of  the  crater,  or  to  the  fact  that  it  is  not  possible  to  get  the 
point  of  the  flame  far  enough  into  the  hole  to  melt  it.  The  only 
way  to  avoid  them  is  to  move  the  torch,  giving  the  tip  a  cir- 
cular motion  around  the  hole,  until  the  surrounding  metal  is 
brought  to  a  temperature  sufficiently  high  to  prevent  the  con- 
duction of  heat,  when  a  sudden  lifting  of  the  torch  will  allow 
the  metal  to  flow  together. 

In  the  case  of  thin  sections,  this  circular  motion  of  the  torch 
has  been  found  to  be  the  most  satisfactory  way  to  weld  steel. 


Fig.  2.   Graphic  Illustration  of  Movement  of  Torch  when 
Welding  Steel 

It  is  very  difficult  to  describe,  but  once  seen  it  is  easy  to  under- 
stand. The  author  knows  of  nothing  that  it  resembles  so  much 
as  a  helical  spring  crushed  down  sideways,  as  shown  in  Fig.  2, 
the  torch  tip  following  the  path  of  the  spring  wire,  advancing  a 
little,  as  from  coil  to  coil,  at  each  revolution.  The  speed  of  ro- 
tation and  advance  have  to  be  made  to  suit  the  work.  Of  course, 
in  heavy  welds  this  cannot  be  done,  as  metal  is  added.  In  this 
case,  the  wire  should  be  used  as  a  sort  of  a  center  around  which 
the  torch  is  oscillated,  the  path  being  somewhat  more  than  a 
half  circle.  In  this  case,  the  wire  should  never  be  removed 
from  the  pool  of  melted  steel,  as  the  tendency  is  then  to  burn 
it.  The  flame  should  not  be  turned  directly  against  the  weld- 
ing-wire, but  kept  far  enough  away  from  it  so  that  while  the 
wire  is  melted,  the  flame  does  not  touch  it;  and  the  flame  should 
not  be  kept  on  the  metal  any  longer  than  is  absolutely  necessary. 


170  WELDING   STEEL 

Steel  does  not  form  a  comparatively  large  melted  pool,  as  in 
the  case  of  cast  iron,  and  for  this  reason,  and  because  of  its 
rapid  solidification,  it  is  necessary  to  be  careful  about  welding 
the  edges  of  the  pool.  As  soon  as  the  metal  is  brought  to  the 
melting  point,  if  the  torch  is  raised  suddenly,  the  metal  which 
has  been  blown  into  a  shallow  cup  shape  by  the  force  of  the 
blast  will  at  once  become  level  and  solidify.  Hence,  a  good 
steel  welder  keeps  his  torch  constantly  in  motion,  using  the 
rotary  movement  and  quick  elevation. 

Size  of  Torch  Tip.  —  From  what  has  been  said  of  the  danger 
of  burning  steel,  it  is  evident  that  it  is  important  to  use  the 
right  size  of  tip,  neither  too  large  nor  too  small,  and  also  to 
provide  sufficient  sizes  of  wire  to  prevent  the  burning  to  which 
it  is  liable.  The  author  finds  that  three  sizes  are  sufficient  for 
the  majority  of  the  work  of  an  ordinary  welding  shop  —  -jV,  £, 
and  T3e  inch. 

Importance  of  Neutral  Flame.  —  It  is  evident  that,  on  ac- 
count of  the  affinity  of  iron  for  oxygen  at  a  high  temperature, 
the  flame  should  be  neutral,  and  not  only  this,  but  there  should 
be  no  oxygen  escaping  from  the  torch  where  it  can  combine 
with  the  melted  metal.  This  is  particularly  important  in  the 
case  of  steel.  The  author  knows  of  instances  where  it  was  im- 
possible with  a  certain  type  of  torch  to  produce  satisfactory 
welds,  while  another,  which  used  less  oxygen,  gave  entirely  sat- 
isfactory results.  This  emphasizes  the  importance  of  good 
apparatus. 

Heat-treatment  of  Welded  Steel.  —  It  should  be  remem- 
bered that  the  weld  is  only  a  casting,  and  that  it  has  received 
no  forging  or  other  treatment  to  refine  the  grain  and  to  make 
the  metal  of  better  quality.  In  a  few  cases  an  extra  amount  of 
metal  can  be  added  to  the  weld  and  the  piece  drawn  out  with 
a  hammer,  or  otherwise  worked  to  produce  a  stronger  metal, 
but  this  cannot  generally  be  done  where  the  dimensions  of  a 
piece  must  be  maintained.  It  is  possible,  however,  by  heat- 
treatment,  to  increase  the  tensile  strength  and  elastic  limit  of 
the  metal  to  a  certain  extent. 

The  physical  characteristics  of  a  weld  in  steel  depend  con- 


WELDING   STEEL  171 

siderably  upon  the  heat-treatment  to  which  it  is  subjected  after 
the  welding  is  done.  This  statement  is  true,  of  course,  of  any 
piece  of  steel  whether  welded  or  not,  and  the  higher  the  amount 
of  carbon,  the  greater  the  effect  of  a  proper  heat-treatment. 
As  already  stated,  it  is 'generally  the  practice  to  use,  for  welding 
steel,  a  wire  either  of  pure  Swedish  iron,  or  of  steel  very  low  in 
carbon.  This  is  done  whether  the  material  to  be  welded  i& 
wrought  iron,  which  contains  very  little  carbon,  or  axle  steel 
containing  0.4  per  cent  of  carbon,  and,  in  many  cases,  such 
welding-wire  is  used  for  steel  containing  still  higher  carbon. 
Now,  inasmuch  as  the  heat-treatment  that  will  give  the  best 
physical  characteristics  depends  upon  the  carbon  content  of 
the  steel,  it  is  evident  that,  unless  the  piece  welded  is  of  a  steel 
very  low  in  carbon,  the  heat-treatment,  to  obtain  the  best  re- 
sults, should  be  different  for  the  added  material  than  for  the 
original.  It  is,  of  course,  impossible  to  do  this,  so  that  a  com- 
promise must  be  effected.  Again,  it  must  be  remembered  that 
a  weld  is  a  casting,  and  that  the  necessary  temperature  for  an- 
nealing a  steel  casting  is  considerably  higher  than  for  a  piece 
of  forged  steel  containing  the  same  percentage  of  carbon.  Again, 
the  higher  the  carbon  content,  the  lower  the  heat-treatment 
temperature  at  which  the  best  results  are  obtained,  so  that  on 
one  hand  there  is  in  the  weld  a  material  low  in  carbon  which  is 
a  casting,  and  which  requires  a  high  heat-treatment  tempera- 
ture to  obtain  good  physical  characteristics,  and,  on  the  other 
hand,  there  is  in  the  original  material,  possibly  a  steel  very  high 
in  carbon,  which  is  a  forging.  Both  conditions  require  a  lower 
temperature  to  obtain  the  best  results,  so  that,  if  the  weld  is 
heated  enough  to  refine  the  grain,  the  original  material  is  over- 
heated, and  while,  in  the  case  of  medium-carbon  steels,  this 
does  not  affect  the  strength  of  the  original  material  very  greatly, 
it  does  affect  it  somewhat. 

Heat-treatment  Temperatures.  —  It  has  been  frequently 
stated  that  a  weld  can  be  annealed  by  heating  to  the  point  at 
which  an  ordinary  horseshoe  magnet  just  ceases  to  be  attracted 
by  the  hot  steel.  This  is  about  right  in  the  case  of  a  piece  of 
forged  steel,  but  this  temperature  is  not  high  enough  in  the  case 


172  WELDING   STEEL 

of  a  weld;  a  temperature  between  1750  and  1800  degrees  F.  is 
necessary  to  break  up  the  coarse  structure  of  a  weld  made  with 
soft  steel  welding-wire.  If  1800  degrees  F.  is  not  exceeded,  no 
serious  damage  will  occur  to  steel  containing  less  than  0.3  per 
cent  of  carbon;  but  the  higher  the  carbon  content,  the  greater 
the  damage  to  the  original  material  by  such  a  high  heat-treat- 
ment temperature. 

It  is  not  possible  in  many  cases  to  heat-treat  a  welded  piece; 
and  in  these  instances  the  physical  characteristics  of  the  weld 
and  adjacent  material  cannot  be  changed.  This  is  the  reason 
why  it  is  so  important  to  use  good  judgment  in  steel  welding, 
and  not  to  weld  pieces  the  original  condition  of  which  has  been 
obtained-  by  carefully  applied  heat-treatment.  Even  in  the 
cases  where  heat-treatment  can  be  applied,  it  is  impossible  to 
obtain  the  same  results  as  in  the  original  piece. 

The  Committee  on  Heat-treatment  of  the  American  Society 
for  Testing  Materials,  recommends,  for  annealing  carbon  steel 
castings,  the  following  approximate  temperatures: 

Carbon,  Per  Cent  Temperature  in  Degrees  F. 

Up  to  0.16  1700 

0.16  to  0.34  1600 

0.35  to  0.54  1560 

0.55  to  0.79  1525 

The  following  statement  is  made  by  Speller  in  the  above 
connection:  "It  will  be  found  in  annealing  large  quantities  of 
soft  steel  under  o.io  per  cent  of  carbon  that  the  temperature 
given  is  about  90  degrees  F.  too -low  to  secure  uniform  refine- 
ment of  grain." 

With  regard  to  annealing  welds  by  heating  to  the  temperature 
at  which  a  magnet  loses  its  attraction  for  the  heated  metal, 
this  loss  of  magnetic  power  occurs  at  from  1330  to  1375  degrees 
F.  on  heating.  It  would,  therefore,  appear  evident  that  the 
use  of  a  magnet  will  not  give  satisfactory  results,  and  that  a 
pyrometer  is  really  the  only  means  for  obtaining  proper  anneal- 
ing temperatures. 

Heat-treatment  of  Alloy  Steels.  —  The  heat- treatment  of 
alloy  steels  is  quite  a  complicated  process,  and  can  only  be 
carried  out  with  the  proper  apparatus.  No  welding  shop,  as  a 


WELDING  STEEL  173 

rule,  has  any  facilities  for  doing  this  work,  and  as  the  ordinary 
welding-rod  does  not  have  the  necessary  ingredients  to  make  a 
truly  homogeneous  weld,  and  as  at  the  best  the  weld  is  only  a 
casting,  the  welding  of  alloy  steels  should  be  avoided.  It  is 
true  that  in  special  cases,  and  where  there  is  a  knowledge  of  the 
character  of  the  metal,  fair  results  may  be  obtained,  but  this 
information  is  not  possessed  by  the  average  welding  shop  doing 
repair  work,  and  it  is  best  to  restrict  the  welding  operation  to 
materials  which  it  is  known  can  be  welded  successfully,  because 
no  good  comes  from  attempting  work  beyond  the  limitations  of 
the  process. 

General  Considerations.  —  It  would  appear  at  first  sight  per- 
fectly feasible  to  use  welding  as  a  process  for  joining  steel  parts 
wherever  riveting  is  now  employed.  In  many  cases  it  is  pos- 
sible to  do  so,  but  in  many  other  cases  it  is  not  advisable.  While 
a  riveted  joint  is  imperfect  in  many  respects,  and  a  poor  mechan- 
ical construction,  yet  its  strength  and  the  practices  followed  in 
making  it  are  so  well  known  that  the  riveted  joint  is  certain  to 
remain.  The  lack  of  knowledge  of  the  technique  of  welding,  the 
scarcity  of  competent  welders,  and  the  prices  of  the  gases  often 
make  the  cost  of  welding  prohibitive  and  the  quality  of  the  work 
uncertain,  when  an  attempt  to  replace  a  riveted  joint  is  made. 
The  time  will  come  when  large  structural  work  will  be  done  by 
the  oxy-acetylene  process.  However,  the  welding  of  steel  by 
this  process  is  being  extended  every  day,  and  things  are  done 
now  which  were  not  thought  possible  a  few  years  ago.  There- 
fore, the  further  extension  of  the  possibilities  may  be  reason- 
ably expected. 

Many  of  the  defects  which  occur  in  a  cast-iron  weld  are  likely 
to  occur  in  a  steel  weld,  some  of  them  being  more  frequent  and 
more  difficult  to  avoid.  The  most  serious  is  a  lap  of  the  hot 
metal  on  top  of  the  cold;  this  is  an  exceedingly  common  defect 
with  new  welders.  It  is  much  more  likely  to  occur  in  a  large 
piece  than  in  a  small  one;  in  fact,  the  larger  the  piece  of  steel, 
the  more  difficult  it  is  to  make  a  sound  weld.  The  difficulty  is 
caused  either  by  the  addition  of  too  much  steel  at  once,  so  that 
it  flows  over  onto  the  metal  underneath  without  being  welded 


174 


WELDING   STEEL 


to  it;  by  dropping  the  metal  from  the  welding  wire  onto  the 
metal  underneath, .instead  of  keeping  the  end  of  the  wire  in  the 
pool  of  melted  metal;  or  by  carelessness  in  not  thoroughly  weld- 
ing the  edges  of  the  melted  pool  to  the  rest  of  the  metal.  The 
metal  is  far  more  likely  to  bridge  in  the  case  of  steel  than  in  the 
case  of  cast  iron,  particularly  where  the  pieces  are  V'd  from 
both  sides,  when  the  weld  is  started  at  the  bottom  of  the  second 
V  after  turning  the  piece  over. 

Fig.  3  shows  an  enlarged  view  of  a  defective  weld,  the  origi- 
nal piece  being  i|  inch  in  diameter.  A  large  number  of  laps 

and  cold-shuts  will  be 
distinctly  noticed.  The 
polishing  to  which  this 
piece  was  subjected  has 
brought  out  the  differ- 
ence between  the  orig- 
inal metal  and  the 
added  material,  and  it 
appears  clearly  that  the 
weld  was  imperfectly 
made,  because  this 
added  material  shows 
on  four  sides.  In  mak- 
ing a  steel  weld,  the 
edges  of  the  weld  should 
be  built  out  somewhat  beyond  the  sides  of  the  original  pieces, 
so  that  it  will  not  be  necessary  to  burn  down  any  on  the  sides 
to  eliminate  imperfect  work.  The  weld  should  be  so  made  that 
any  roughness  left  on  it  when  ground  off  will  leave  sound  metal 
all  the  way  around.  There  is  always  great  danger  of  laps  or 
cold-shuts  when  any  other  course  is  followed.  This  is  particu- 
larly applicable  to  round  pieces,  which  are  more  difficult  to  weld 
than  rectangular  ones. 

Welding  High-speed  Steel  to  Machine  Steel. —  To  weld 
high-speed  steel  to  ordinary  machine  steel,  first  heavily  coat  the 
end  of  the  high-speed  steel  with  soft  special  iron,  obtainable 
from  the  makers  of  welding  outfits.  This  can  be  done  without 


Fig.  3.   Section  of  Defective  Weld  in  Steel  Bar 


WELDING   MALLEABLE   IRON  175 

heating  the  high-speed  steel  to  the  burning  point.  After  cool- 
ing, the  high-speed  steel  can  be  welded  to  ordinary  machine 
steel  without  burning,  but  experience  is  required  to  make  a 
good  weld  of  this  kind. 

Welding  Cast  Iron  to  Steel.  —  To  weld  cast  iron  to  steel, 
cast-iron  rods  are  used  as  welding  material.  The  steel  must  be 
first  heated  to  the  melting  point,  as  cast  iron  melts  at  a  lower 
temperature.  A  very  little  cast-iron  flux  should  be  used. 

Welding  Steel  Castings.  —  Certain  grades  of  steel  castings 
can  be  welded  more  easily  than  ordinary  rolled  steel,  but  other 
grades,  especially  of  high  carbon  content,  are  very  difficult  to 
weld,  and  some  cannot  be  welded  at  all.  When  difficulty  is 
experienced,  the  addition  of  one  or  two  drops  of  copper,  melted 
into  the  weld,  will  cause  the  metal  to  flow  and  a  fairly  good  weld 
can  be  made,  but  copper  is  likely  to  harden  the  metal  so  that 
it  cannot  be  machined  except  by  grinding. 

Spots  in  Welding.  —  When  making  heavy  welds,  there  often 
is  a  spot  in  the  middle  of  a  weld  where  the  metal  refuses  to  flow, 
because  the  metal  is  not  hot  enough  surrounding  this  spot,  the 
heat  being  absorbed  by  the  cold  metal;  consequently,  the  added 
metal  is  chilled.  To  remedy  this,  play  the  flame  in  a  radius  of 
from  \  to  i  inch  around  the  refractory  point  until  the  surround- 
ing metal  is  at  a  white  heat;  then  apply  the  flame  to  the  spot 
itself  and  it  will  quickly  unite  with  the  other  molten  metal. 

Welding  Malleable  Iron.  —  The  welding  of  malleable  iron 
is  difficult,  for  several  reasons.  If  malleable  iron  is  raised  to 
the  melting  point  and  kept  there  for  any  length  of  time,  the 
metal  becomes  spongy  and  changes  to  what  is  practically  cast 
iron.  Those  who  have  tried  to  weld  malleable  iron  know  that 
the  results  are  usually  unsatisfactory.  The  metal  either  becomes 
so  hard  that  it  cannot  be  machined,  or  it  is  brittle,  or  both. 
The  reasons  for  this  lie  in  the  nature  of  the  metal,  which  is  not 
generally  understood,  because  of  the  comparative  lack  of  knowl- 
edge of  its  method  of  manufacture.  To  explain  sufficiently  why 
these  difficulties  exist  and  how  they  may  be  overcome,  it  is  neces- 
sary to  consider  somewhat  the  metallurgy  of  cast  iron  and  the 
changes  which  take  place  during  its  conversion  into  malleable  iron. 


176  WELDING  MALLEABLE   IRON 

Production  of  Malleable  Castings.  —  It  is  necessary  in  mak- 
ing malleable  iron  to  use  white  or  chilled  iron  castings,  because 
graphite,  being  an  inert  substance  and  not  acted  on  by  the  mal- 
leabilizing  process,  cannot  have  its  condition  changed  by  this 
process,  so  that  the  carbon  in  iron  from  which  malleable  cast- 
ings are  to  be  made  must  all  be  in  the  " combined"  condition, 
and  not  "free,"  as  in  gray-iron  castings.  Cast  iron  has  a  larger 
percentage  of  carbon  than  steel,  and  it  would  appear  that  if 
enough  of  the  carbon  could  be  removed  from  cast  iron,  so  that 
it  had  about  as  much  as  ordinary  steel,  a  product  resembling 
steel  would  be  the  result.  This  was  the  aim  of  the  inventor  of 
malleable  iron,  Reaumur,  and  the  process  was  carried  out  by 
packing  the  white  cast-iron  pieces  in  decarburizing  matter,  such 
as  oxide  of  iron,  and  subjecting  the  pieces  so  packed  to  a  high 
temperature  for  a  long  enough  time  to  reduce  the  percentage  of 
carbon  to  the  desired  point.  It  was  found  that  the  time  required 
to  carry  the  action  entirely  through  a  piece  was  considerable, 
and,  therefore,  the  cost  was  excessive;  so  that  only  thin  pieces 
are  now  subjected  to  this  process.  Inasmuch  as  it  was  desirable 
to  treat  heavier  pieces,  it  was  found  by  experiment  that  it  was 
not  necessary  to  reduce  the  percentage  of  carbon  all  the  way 
through  the  piece,  but  that,  by  proper  treatment  in  the  anneal- 
ing oven,  the  carbon  could  be  changed  into  a  third  form  to  which 
has  been  given  the  name  "temper"  carbon,  to  distinguish  it 
from  "combined"  and  "free"  carbon,  although  temper  carbon 
is  identical  with  graphite  as  far  as  can  be  determined. 

The  first  kind  of  malleable  iron  can  generally  be  welded  with 
steel,  as  it  is  really  a  crude  steel.  The  second  form,  however,  is 
the  one  that  presents  the  difficulties  spoken  of  above,  and  it  will 
now  be  evident  why  these  difficulties  exist.  Cast  iron,  when 
changed  into  steel,  cannot,  by  melting  under  the  torch,  be 
changed  into  cast  iron  again;  but  in  the  second  kind  of  mal- 
leable iron,  the  carbon  is  not  removed,  but  only  changed  into 
another  form.  Therefore,  when  melted,  all  the  conditions  are 
favorable  to  the  reformation  of  chilled  iron,  which  is  exactly 
what  occurs;  so  that  the  resulting  weld  is,  as  previously  stated, 
hard  and  brittle. 


WELDING  MALLEABLE   IRON  177 

Procedure  in  Welding  Malleable  Iron.  —  Malleable  iron  can 
be  welded  with  a  cast-iron  welding-rod  and  a  sound  weld  ob- 
tained, but  it  is  not  homogeneous.  In  some  cases,  it  may  be 
entirely  satisfactory;  for  instance,  where  special  strength  is  not 
required,  or  where  no  finishing,  except  by  grinding,  is  to  be  done. 
For  all  ordinary  work,  it  has  been  found  that  the  use  of  man- 
ganese-bronze as  a  welding-rod  with  a  little  borax  used  as  a 
flux  will  make  a  weld,  which,  while  not  homogeneous,  will  an- 
swer the  purpose.  The  precautions  to  be  observed  are  as  follows: 

i.  Malleable  iron  must  not  be  melted,  but  only  brought  to  a 
temperature  at  which  the  bronze  will  alloy  with  it.  This  is 
somewhat  above  a  good  red  heat,  and  is  easily  ascertained  by  a 


Fig.  4.   Malleable  Iron  improperly  welded 

few  trials.     A  neutral  flame  must  be  used,  and  it  is  generally 
advisable  to  add  surplus  metal  to  the  weld. 

2.  It  is  a  good  thing  for  the  welder  to  observe  the  action  of 
the  second  kind  of  malleable  iron  under  the  torch.  It  will  be 
noticed  in  a  fresh  break  that  the  outside  shell,  say,  -5%  inch  deep, 
is  white,  and  under  the  torch  acts  like  steel,  but  the  further  in 
toward  the  center  the  flame  is  used,  the  more  will  the  action 
appear  like  that  of  cast  iron,  and  it  will  be  found  that  steel  can- 
not be  used  in  welding.  The  metal  also  tends  to  become  full  of 
blow-holes.  If  the  torch  is  used  to  melt  such  a  piece,  and  it  is 
then  allowed  to  cool  off  and  the  surface  ground  and  polished,  it 
will  be  found  to  consist  of  white  iron,  except  the  thin  outside 
shell.  If  a  weld  is  made  using  a  malleable  iron  welding-rod,  it 
will  be  found  that  the  weld  is  very  brittle,  and,  when  broken, 
will  show  the  characteristic  appearance  of  white  iron.  Of  course, 


178  WELDING  MALLEABLE   IRON 

such  a  weld  may  be  made  into  malleable  iron  by  putting  it 
through  the  regular  process,  but  this  is  not  possible  in  repair 
work,  although  it  is  in  certain  manufacturing  processes.  There- 
fore, the  use  of  bronze  appears  to  be  the  only  present  solution 
of  the  difficulty,  and  it  would  seem  that  the  metallurgy  of  mal- 
leable iron  makes  impossible  any  other  solution. 

Effect  of  Improper  Welding.  —  Figs.  4,  5,  and  6  are  good  il- 
lustrations of  the  structure  of  malleable  iron  and  of  the  damage 
done  to  it  by  improper  welding.  Fig.  4  shows  the  section  nearly 
full  size,  while  the  others  are  enlarged  to  show  the  defects  more 
clearly.  There  is  considerable  difference  in  appearance  between 


Fig.  5.   One  End  of  Piece  shown  in  Fig.  4,  magnified 


the  outside  and  inside  of  the  piece.  The  piece  was  originally 
welded  with  steel.  The  second  break  occurred  outside  the  weld, 
because  the  added  steel  at  the  first  weld  was  considerable  in 
amount,  and,  therefore,  stronger  than  the  section  shown. 

In  Fig.  4  the  difference  between  the  center  and  the  outside 
of  malleable  iron  is  very  clear,  the  outside  being  darker  and  of 
steel,  while  the  inside  is  of  cast  iron,  but  with  the  carbon  changed 
to  the  "temper"  form.  Wherever  the  added  steel  is  welded  to 
the  steel  casing,  the  metal  at  the  junction  of  the  cast  iron  and 
steel  has  been  seriously  damaged,  causing  holes;  and  where 
there  is  no  added  steel,  or  where  the  weld  between  the  two  steels 
has  been  defective,  as  from  A  to  B,  Fig.  6,  no  apparent  damage 


WELDING   COPPER  1 79 

has  occurred.  An  examination  of  the  piece  shows  that  no  extra 
metal  was  added  from  C  to  D  or  from  E  to  F,  and  that  on  ac- 
count of  the  defective  weld  between  the  two  steels  at  A  and  B, 
no  apparent  damage  is  done  to  the  metal  below. 

In  repairing  the  break,  it  was  found  impossible  to  cut  the 
defective  pieces  out  with  a  hacksaw,  as  hard  spots  were  encoun- 
tered as  soon  as  the  added  steel  was  cut  through.  It  was,  there- 
fore, necessary  to  grind  the  defective  parts  away.  This  left  a 
space  which  had  to  be  filled  up,  which  was  done  with  manganese- 
bronze,  the  weld  being  made  and  heavily  reinforced  with  the 


Fig.  6.   The  Other  End  of  Piece  shown  in  Fig.  4,  magnified 

same  metal.  The  hard  spots  were  caused  by  the  malleable  iron 
changing  back  to  white  or  chilled  iron  under  the  high  heat  used. 
Welding  Copper  and  Copper  Alloys.  —  Under  this  heading 
will  be  treated  the  welding  of  pure  copper  and  also  the  various 
kinds  of  brass  and  bronze  which  are  made  with  copper  as  the 
principal  ingredient.  Copper  is  not  a  difficult  metal  to  weld  if 
precautions  are  observed  to  avoid  several  peculiarities  in  its 
action  when  under  a  high  temperature.  It  has  the  property, 
when  melted,  of  absorbing  gases  to  a  very  considerable  extent. 
On  cooling,  these  gases  are  given  out  and  make  the  weld  porous. 
Copper  also  oxidizes  readily  when  melted  and  this  oxide  alloys 


l8o  WELDING  COPPER 

with  the  copper,  making  it  brittle  and  spoiling  the  weld.  As  it 
is  impossible  to  work  out  this  oxide,  methods  must  be  used  during 
the  welding  to  eliminate  it,  or  preferably,  to  avoid  it  altogether. 

Use  of  Phosphorus  in  the  Welding-rod.  —  It  has  been 
known  for  a  long  tune  that  a  small  percentage  of  phosphorus 
added  to  copper  or  copper  alloys  eliminates  blow-holes  and 
makes  a  sound,  dense  casting;  hence,  the  welding-rod  for  cop- 
per should  contain  the  proper  percentage  of  phosphorus.  Traces 
of  phosphorus  do  not  injure  copper,  but  an  excess  is  not  good, 
so  that  proper  care  and  accurate  knowledge  are  necessary  to 
produce  the  proper  welding  material.  Copper  has  great  heat- 
conducting  power  —  more  so  than  any  of  the  other  common 
metals  —  and  while  it  melts  at  about  1930  degrees  F.  the  heat 
is  removed  so  rapidly  by  conduction  that  it  is  necessary  to  use 
a  larger  tip  than  for  iron  and  steel;  and  preheating  of  the  parts 
is  more  necessary  in  order  to  reduce  the  gas  consumption  than 
in  the  case  of  other  metals.  The  radiation  from  the  heated  metal 
may  be  retarded  by  covering  it  with  asbestos.  On  account  of 
the  affinity  of  copper  for  oxygen,  and  on  account  of  the  fact 
that  an  excess  acetylene  flame  produces  blow-holes  in  the  weld, 
even  with  good  welding  material,  it  is  necessary  t6  use  a  neutral 
flame,  although  it  will  be  found  that  instructions  are  sometimes 
given  to  the  contrary. 

Miscellaneous  Precautions  in  Copper  Welding.  —  Another 
peculiarity  of  copper  is  its  brittleness  at  a  temperature  some- 
what above  a  dull  red,  while  at  or  below  this  temperature  it 
can  be  readily  forged.  The  welder  must,  therefore,  be  careful 
to  observe  contraction  strains  as  the  metal  is  cooling  down. 
Full  and  uniform  preheating  will  help  to  avoid  this  difficulty. 
It  is  not  often,  however,  that  a  repair  welding  shop  is  called  on 
to  work  with  copper,  and  when  it  is,  the  work  is  generally  the 
simple  welding  of  rods  or  bars  together.  In  such  cases,  enough 
metal  should  be  added  to  make  a  considerable  " swell"  around 
the  weld,  and,  after  heating  to  a  dull  red,  it  should  be  forged. 
Care  should  be  taken  not  to  heat  it  too  hot,  and  after  the  forg- 
ing is  done,  the  work  should  be  allowed  to  cool  off  slowly,  unless 
it  has  to  be  bent,  when  the  whole  piece  should  be  heated  to  a 


WELDING  COPPER  181 

dull  red  and  annealed  by  plunging  it  in  water,  this  operation 
being  repeated  frequently  if  the  piece  requires  much  working, 
as  the  working  of  the  metal  causes  it  to  become  brittle. 

A  method  for  welding  copper,  which  is  claimed  to  give  very 
satisfactory  results,  consists  in  placing  two  pieces  of  copper  in 
position,  so  that  they  can  be  heated  at  the  proper  point  by  the 
oxy-acetylene  torch  until  the  requisite  degree  of  softness  is  at- 
tained. Complete  reduction  is  then  effected  in  the  flame  by 
the  use  of  purified  hydrogen,  and  the  welding  is  completed  by 
hammering.  The  joint  is  said  to  be  invisible  and  the  metal  at 
the  weld  is  claimed  to  be  as  homogeneous  in  every  way  as  the 
remainder  of  the  metal  welded;  but  this  method  is  not  appli- 
cable in  ordinary  cases,  although  it  may  be  useful  in  certain 
manufacturing  operations. 

Recapitulation  of  General  Directions  for  Welding  Copper.  - 
In  welding  copper,  use  the  same  kind  of  flame  as  for  steel,  but  a 
much  larger  tip  for  corresponding  dimensions,  because  of  the 
great  radiating  property  of  copper.  Preheating  is  necessary 
when  a  large  piece  of  copper  is  to  be  welded,  as  otherwise  so 
much  heat  from  the  torch  will  be  dissipated  by  radiation  that 
little  will  be  left  for  fusing  the  metal.  Copper  will  weld  at  about 
1930  degrees  F.;  hence,  the  flame  need  not  have  so  high  a  tem- 
perature as  for  steel  and  it  must  not  be  concentrated  on  so  small 
a  surface.  On  account  of  the  radiation,  however,  the  total 
quantity  of  heat  must  be  greater.  Welded  copper  has  the 
strength  of  cast  copper,  but  can  be  rendered  more  tenacious  by 
hammering.  The  radiation  of  heat  from  copper  can  be  con- 
siderably lessened  by  covering  it  with  asbestos  sheets  while 
heating. 

To  Weld  Copper  to  Steel.  —  To  weld  copper  to  steel,  first 
raise  the  steel  to  a  white  heat  (the  welding  point);  then  put 
the  copper  into  contact  with  it  and  the  two  metals  will  fuse 
together.  When  the  copper  begins  to  flow,  withdraw  the  flame 
slightly  to  prevent  burning. 

Copper  Alloys.  —  Copper  alloys  are  divided  into  two  general 
classes,  brasses  and  bronzes.  The  principal  ingredients  in  the 
former  are  copper  and  zinc,  and  in  the  latter,  copper  and  tin. 


1 82  WELDING   COPPER 

There  are  a  great  number  of  these  alloys  differing  materially  in 
composition,  and  as  the  welder  cannot  know  the  exact  composi- 
tion of  each,  and  as,  even  if  he  did,  it  would  be  impossible  to 
make  the  proper  mixture  to  produce  a  truly  homogeneous  weld, 
a  welding  material  should  be  kept  in  stock  that  will  cover  all 
of  the  cases  with  which  he  meets.  It  is  the  general  experience 
that  manganese-bronze  or  Tobin  bronze  is  very  satisfactory  for 
all  brasses  and  bronzes. 

In  welding  brass,  when  the  metal  is  brought  to  a  certain 
temperature  by  the  torch,  white  fumes  suddenly  disengage 
themselves,  and,  in  the  case  of  a  large  piece,  these  will  chill  and 
condense  on  the  cooler  surfaces.  This  is  due  to  the  volatilization 
of  the  zinc,  the  fumes  being  white  zinc-oxide;  care  should  be 
taken  not  to  breathe  these  fumes.  The  proper  point  at  which 
to  add  the  metal  is  just  after  the  surface  of  the  piece  begins  to 
boil  and  bubble,  and  as  manganese-bronze  contains  a  large  per- 
centage of  zinc,  any  zinc  that  may  be  lost  in  heating  will  be 
partly  replaced  by  the  metal  in  the  welding-rod.  In  the  case  of 
bronze,  the  zinc  loss  does  not  occur,  but  the  bubbling  of  the 
surface  of  the  heated  piece  occurs  and  determines  the  tempera- 
ture at  which  the  metal  should  be  added.  Manganese-bronze  is 
quite  fluid  and  unites  nicely  with  the  broken  parts.  It  is  ad- 
visable to  use  a  small  amount  of  borax  as  a  flux  to  clean  the 
surface,  although  no  more  than  is  necessary  should  be  used. 

A  neutral  flame  is  the  proper  one  to  use  for  both  brass  and 
bronze.  Keep  the  point  of  the  white  flame  slightly  away  from 
the  weld,  according  to  the  thickness  of  the  piece,  so  that  the 
heat  will  not  be  sufficient  to  burn  the  copper  in  the  brass  or  to 
appreciably  volatilize  the  zinc.  If  a  white  smoke  appears,  re- 
move the  flame,  as  this  indicates  excessive  heat.  Brass  and 
bronze  are  both  good  heat  conductors,  although  not  as  good  as 
copper.  Generally  the  same  size  tip  as  for  cast  iron  will  be  sat- 
isfactory. Care  should  be  taken  to  avoid  laps  or  cold-shuts  in 
a  weld,  which  is  readily  done  if  the  metal  is  kept  at  the  proper 
temperature.  These  metals  are  generally  easy  to  weld,  and,  as 
manganese-bronze  is  exceedingly  strong,  the  weld  is  generally 
the  strongest  part  of  the  piece. 


WELDING  COPPER  183 

Filling  Blow-holes.  —  To  fill  large  blow-holes  in  brass  or 
copper  castings,  preheat  the  casting  to  a  temperature  between 
200  and  400  degrees  F.  below  the  melting  point,  or  to  a  bright 
red  color.  Have  some  of  the  same  metal  melted  in  a  crucible 
ready  to  pour,  then  apply  the  torch  to  the  blow-hole  to  be 
filled  and  when  the  walls  of  the  hole  have  been  brought  to  the 
melting  point,  gradually  pour  in  the  metal,  keeping  the  walls 
fused  by  using  the  flame.  Continue  mixing  the  poured  metal 
with  the  molten  metal  of  the  walls,  until  the  blow-hole  is  filled. 
This  method,  however,  is  only  used  when  a  sound  job  is  not 
required,  but  the  filling  is  done  for  appearance  only.  It  is  not 
a  generally  satisfactory  method,  as  "burning-in"  does  not  pro- 
duce homogeneous  metal,  and  one  cannot  see  what  is  taking 
place  at  the  weld. 


CHAPTER  VII 
WELDING  ALUMINUM 

ALUMINUM  is  seldom  used  in  its  pure  condition,  as  it  is  too 
soft,  and  in  repair  work,  only  the  aluminum  alloys  —  princi- 
pally in  the  form  of  crankcases,  transmission  cases,  and  other 
automobile  parts  —  are  encountered.  In  the  United  States,  the 
usual  alloy  contains,  at  the  present  time,  about  93  per  cent  of 
aluminum  and  7  per  cent  of  copper.  In  the  past,  quite  a  num- 
ber of  parts  were  made  from  a  zinc  alloy  containing  approxi- 
mately 90  per  cent  of  aluminum  and  10  per  cent  of  zinc,  but  in 
foundry  practice  it  was  found  that  the  alloy  became  brittle  at 
a  temperature  just  below  solidification,  so  that  many  castings 
were  defective  on  account  of  cracks  due  to  shrinkage  and  had 
to  be  thrown  out.  The  copper  alloy,  while  not  quite  so  strong 
at  ordinary  temperatures,  does  not  have  the  tendency  to  crack 
that  the  zinc  alloy  has;  this  is  fortunate  for  the  welder,  as  crack- 
ing is  likely  to  occur  in  many  cases,  particularly  in  a  compli- 
cated piece,  due  to  the  contraction  strains. 

Flux  for  Aluminum  Welding.  —  It  is  frequently  stated  that 
it  is  impossible  to  make  a  sound  weld  in  aluminum  without  a 
flux  which  will  destroy  the  oxide.  Aluminum  oxide  is  exceed- 
ingly resistant  to  the  action  of  any  acid  or  alkali  even  at  a  high 
temperature.  Therefore,  the  flux  used  in  welding  must  be  very 
severe  in  its  action.  The  danger  in  using  some  kinds  of  flux  is 
that  an  excess,  unless  it  is  removed  in  some  way,  will  damage 
both  the  metal  in  the  weld  and  that  surrounding  it.  Another 
objection  to  the  use  of  flux  is  that  the  surfaces  to  be  joined  must 
be  thoroughly  cleaned,  because  the  flux  is  designed  to  remove 
oxide  of  aluminum  and  not  grease  and  dirt,  which  are  always 
present  in  repair  work.  The  tune  occupied  in  cleaning  the  dirt 
out  of  the  crack  or  break  is  considerable,  and  in  most  cases  the 
weld  can  be  made  without  flux  in  the  time  required  to  clean  the 

184 


WELDING   ALUMINUM 


185 


piece  thoroughly.  Again,  it  is  not  possible,  even  by  the  use  of  a 
flux,  to  avoid  some  porosity  in  a  weld;  and  further,  in  the  best 
aluminum  castings  there  may  be,  and  frequently  is,  greater 
porosity  than  in  a  well-puddled  weld.  In  view  of  these  facts, 
the  author  doubts  the  advisability  or  necessity  of  using  flux  on 
castings.  (See  Chapter  III.) 

Welding  without  Flux.  —  The  method  recommended,  and 
which  is  used  by  many  experienced  welders  in  the  case  of  cast 
aluminum,  is  to  thoroughly  puddle  it  without  any  preparation, 
except  wiping  off  the  dirt  and  grease.  There  is  an  additional 


Fig.  1.   Crankcase  damaged  by  Use  of  Flux  and  Improper  Welding 

advantage  in  not  making  a  V  at  the  break  in  the  case  of  alumi- 
num, which  is  that  the  sections  are  generally  thin  and  the  con- 
traction of  the  weld  is  better  resisted  by  the  piece  being  allowed 
to  remain  its  full  thickness,  although  of  course  the  contraction 
is  not  entirely  avoided. 

Result  of  Using  too  Much  Flux.  —  Figs,  i  and  2  show  the 
damage  that  can  be  done  by  improper  treatment.  This  type  of 
crankcase  generally  is  not  seriously  damaged  when  a  connecting- 
rod  or  bolt  gives  way,  which  apparently  was  the  cause  of  the 
damage.  The  welder  used  altogether  too  much  flux  on  it,  and 


1 86  WELDING   ALUMINUM 

was  unable  to  obtain  satisfactory  results.  The  case  was  so 
seriously  damaged  by  this  treatment  that  the  cost  of  putting 
it  in  proper  shape  would  be  much  greater  than  if  it  had  been 
properly  repaired  in  the  first  place,  and  would  be  so  high  that 
it  would  probably  be  inadvisable  to  spend  the  money  on  it. 
This  is  a  good  illustration  of  the  incidental  damage  that  can 
be  done  by  improper  welding.  Undoubtedly,  the  welder  who 
attempted  to  do  this  job  had  had  little,  if  any,  experience,  and 
had  no  instructions  in  the  principles  of  the  art. 


Fig.  2.   Bottom  View  of  Crankcase  shown  in  Fig.  1 

Procedure  in  Welding.  —  A  puddling  rod  such  as  shown  in 
Fig.  3  has  been  found  most  satisfactory,  although  other  shapes 
are  used.  In  all  ordinary  cases,  the  metal  should  be  melted  with 
the  torch  until  the  bottom  of  the  crack  is  reached,  using  the 
puddling  rod  all  the  time,  and  the  metal  should  be  allowed  to 
sink  below  the  lower  surface  of  the  crack,  forming  beads.  These 
beads  can  be  removed  afterward,  either  by  the  torch  and  pud- 
dling rod,  or  by  chipping  or  filing.  In  welding  thick  pieces,  the 
work  must  be  done  from  both  sides.  In  this  case,  too  much  of 
the  welding  should  not  be  made  on  one  side  at  once.  It  is  better 
to  weld,  say,  2  inches,  on  the  first  side,  and  then  turn  the  work 


WELDING   ALUMINUM  187 

over  and  finish  welding  the  2  inches  on  the  other  side,  then  pro- 
ceed along  2  inches  further,  and  again  turn  the  piece  over  and 
weld  2  inches  more  on  the  first  side.  The  reason  for  this  is  that 
aluminum  is  somewhat  brittle  near  the  welding  temperature, 
and  cracks  are  likely  to  develop,  particularly  in  a  long  weld,  if 
all  the  weld  is  made  on  one  side  first,  and  then  finished  on  the 
other.  On  account  of  this  brittleness,  a  weld  in  aluminum 
must  be  made  quickly.  Slow  work  is  fatal  to  good  results.  It 
is  occasionally  necessary  in  a  long  weld  to  have  two  welders 
start  at  the  middle  of  the  crack,  and  work  toward  the  ends, 
to  avoid  shrinkage  cracks. 

Character  of  Flame.  —  It  is  frequently  recommended  that  a 
flame  with  a -slight  excess  of  acetylene  should  be  used  when 
welding  aluminum,  to  prevent  oxidation  and  to  reduce  the  tem- 


J 


Fig.  3.  Puddling  Rod  used  when  Welding  Aluminum 

perature.  A  very  slight  excess  is  all  that  is  needed  for  the  former 
reason,  but  it  has  not  been  found,  in  practice,  necessary  to  use 
such  a  flame,  and  a  neutral  flame  is  recommended.  The  prac- 
tice of  using  an  excess  of  acetylene  doubtless  originated  in  the 
early  days  of  the  process,  when  nearly  all  torches  gave  an  ex- 
cess-of-oxygen  flame,  which  later  and  better  designs  will  not 
do,  and  it  is  not  now  necessary,  with  a  good  torch,  to  use  an 
excess-of-acetylene  flame.  With  regard  to  the  flame  tempera- 
ture, it  is  obvious  that  if  it  is  too  high,  with  a  very  slight  excess 
of  acetylene,  a  smaller  size  of  tip  should  be  used.  There  is  no 
advantage  in  burning  more  gas  than  necessary. 

Preheating.  —  It  is  always  safest  to  preheat  an  aluminum 
casting  to  about  500  degrees  F.,  to  take  care  of  the  contraction 
strains  as  much  as  possible.  During  the  preheating,  the  piece 
should  be  covered  with  asbestos  paper,  to  keep  the  tempera- 
ture as  uniform  as  possible.  This  covering  should  not  be  re- 


1 88  WELDING  ALUMINUM 

moved  while  welding,  except  where  necessary.  After  welding, 
the  part  should  be  reheated,  and  either  allowed  to  cool  in  the 
fire,  or  be  wrapped  in  asbestos  paper  and  allowed  to  cool  slowly 
and  free  from  the  influence  of  drafts.  It  is  generally  true  that 
if  no  crack  appears  in  a  few  minutes  after  welding,  none  will 
occur  at  all;  therefore,  it  is  well  to  leave  the  piece  in  the  fire 
and  examine  it  at  a  short  interval  after  welding.  If  the  weld 
is  sound,  it  can  then  be  packed  away  with  little  fear  of  trouble. 

In  many  cases,  as  with  other  metals,  it  is  not  necessary  to 
preheat;  as,  for  instance,  small  pieces,  or  where  a  lug  or  pro- 
jecting piece  is  broken  off,  the  break  being  at  some  distance 
from  the  main  part  of  the  casting.  In  fact,  in  such  instances 
as  the  breaking  off  of  a  lug  in  an  aluminum  manifold,  preheating 
is  dangerous,  as  too  much  heat  will  tend  to  bring  the  body  of 
the  piece  to  the  temperature  at  which  it  will  suddenly  sink  away 
from  its  original  shape.  The  beginner  will  also,  until  he  learns 
by  experience,  have  the  same  trouble  when  he  lifts  up  a  piece 
to  turn  it  over  before  it  has  set  solidly,  as  it  will  either  distort 
or  fall  to  pieces. 

Manipulation  of  Welding-rod  and  Torch.  —  Too  much  metal 
should  not  be  added  from  the  welding-rod  at  one  time,  and  what 
is  added  should  be  thoroughly  puddled  with  the  welding-rod 
while  it  is  being  added  and  afterward,  until  there  is  a  melted 
pool  at  that  point  and  the  proper  union  has  been  made  with 
the  surrounding  metal.  The  surplus  metal  should  be  scraped 
off  with  the  puddling  rod  while  in  a  pasty  condition,  as  it  con- 
tains much  oxide,  and  the  welder  should  be  sure  to  make  a  good 
junction  at  the  edges  of  the  weld.  The  manipulation  of  the 
torch  with  one  hand  and  the  welding-stick  with  the  other,  the 
latter  having  to  be  laid  down  and  the  puddling-rod  picked  up  at 
frequent  intervals,  is  rather  difficult.  Some  welders  find  it  easier 
to  hold  the  torch  in  the  left  hand,  although  ordinarily  right- 
handed;  others  find  the  opposite  way  to  be  the  easier.  In  either 
case,  the  trouble  is  caused  by  the  difficulty  of  working  with 
both  hands  at  once. 

When  adding  the  metal  from  the  welding-stick,  it  should  be 
continually  rubbed  into  the  melted  pool  in  order  to  avoid  oxi- 


WELDING  ALUMINUM  189 

- 

dation  and  to  work  the  oxide  to  the  surface.  A  beginner  should 
weld  and  break  quite  a  number  of  test-pieces  before  he  attempts 
any  important  work.  He  should  not  be  discouraged  at  the  re- 
sult of  his  first  attempts,  which  are  certain  to  be  unsatisfactory, 
much  more  so  than  with  any  other  metal,  although  aluminum 
is  a  very  easy  metal  to  weld,  after  the  difficulties  in  handling  it 
have  been  overcome. 


Fig.  4.  (A)  Weld  made  by  Beginner.  (B)  Fusion  not  Thorough. 
(C)  A  Good  Weld  on  0.048-inch  Stock.  (D)  A  Good  Weld  on 
0.116-inch  Stock.  (E)  Flanged  Weld  improperly  done.  (F)  A 
Hammered  Flanged  Weld 

Welding  Sheet  Aluminum.  —  The  preceding  paragraphs  re- 
fer especially  to  repair  work  on  castings.  In  the  case  of  sheet 
metal,  the  procedure  is  different.  Before  commencing  to  weld, 
the  edges  of  the  joint  are  carefully  squared,  cleaned,  and  fluxed, 
frequently  by  dissolving  the  flux  in  alcohol  and  painting  it  along 
the  edges  to  be  welded.  Practically  all  work,  except  sheets 
of  very  light  gage  is  butted,  the  thin  sheets  being  lapped  or 
hooked;  or  it  will  be  found  advantageous  at  times  to  turn  up 


t  go 


WELDING  ALUMINUM 


the  edges  at  right  angles  so  as  to  form  sufficient  excess  of  metal 
for  filling  in  the  joint.  By  this  method  it  will  be  clearly  seen 
that  heterogeneous  metal  does  not  enter  the  weld,  the  joint 
being  entirely  composed  of  metal  identical  with  the  surfaces  to 
be  joined. 

The  flame  is  usually  applied  at  an  angle  of  about  45  degrees 
to  prevent  burning,  but  for  thick  sheets  of  -IQ  inch  and  upwards 


Fig.  5.   Fractured  Aluminum  Gear-case  before  and  after  being 
welded  with  Oxy-acetylene  Blowpipe 

it  may  be  directed  nearly  perpendicularly  upon  the  work.  It 
must  be  remembered  that  the  flame  gives  a  temperature  about 
four  tunes  the  melting  point  of  the  metal,  and  that  there  is 
quite  a  blast  from  the  gas  pressures  in  the  torch,  so  that,  in 
thin  metal,  there  is  nothing  to  prevent  holes  from  being  formed 
in  the  aluminum,  except  the  dexterity  of  the  worker.  An  expert 
can  make  good  welds  in  sheet  aluminum  0.008  inch  thick.  Speed 


WELDING  ALUMINUM 


igi 


is  the  prime  requisite,  and  the  welder  should  be  able  to  run  down 
the  joint  with  the  torch  and  rod  at  a  uniform  rate.  In  view  of 
the  great  expansion  of  aluminum  when  heated,  a  considerable 
opening  must  be  left  at  one  end  when  commencing  to  weld, 
which  opening  will,  of  course,  close  up  as  the  work  proceeds. 
While  the  thermal  conductivity  of  aluminum  is  higher  than 
that  of  iron,  this  is  offset  by  the  lower  melting  point,  so  that 
generally  the  same  size  of  tip  can  be  used  for  aluminum  as  for 
cast  iron  of  the  same  thickness. 


Fig.  6.  Aluminum  Manifold  with  Broken  Lug 

General  Requirements  in  Welding  Aluminum.  —  In  welding 
aluminum  with  the  oxy-acetylene  torch,  it  is  essential  that  the 
acetylene  and  the  oxygen  used  must  be  in  a  state  of  high  purity, 
as  at  the  great  temperature  of  the  welding  flame,  aluminum 
tends  to  absorb  nitrogen,  and  if  this  impurity  exists  in  the  oxy- 
gen it  will  render  the  work  brittle  and  unreliable.  It  is  known 
to  those  who  have  attempted  to  weld  aluminum  by  means  of 
the  oxy-acetylene  flame  that,  when  two  pieces  of  the  metal  are 
to  be  welded  together  at  their  edges,  the  melted  parts  do  not 
flow  together  properly,  as  in  the  case  of  iron  where  the  melting 
point  of  the  oxide  is  lower  than  that  of  the  metal.  The  molten 
aluminum  spreads  in  spherical  form  under  the  influence  of  the 


I Q2  WELDING  ALUMINUM 

welding  flame.  These  metallic  pellets  consist  of  pure  aluminum 
within  a  coating  of  alumina  (oxide  of  aluminum)  which  has 
great  power  of  resistance  to  the  flame,  and,  on  cooling,  the  edges 
of  the  metal  remain  unjoined;  hence,  the  need  of  a  flux  to  re- 
move the  oxide  film  and  permit  the  fused  metal  to  flow  satis- 
factorily together. 

Skill  Required  by  the  Welder.  —  The  success  of  welding 
aluminum  autogenously  depends  to  a  great  extent  upon  the  in- 
telligence and  ability  of  the  operator.  It  is  possible  for  a  corn- 


Fig.  7.  Aluminum  Inlet  Manifold  with  Broken  Carburetor  Flange 

petent  welder,  at  his  own  discretion,  to  give  a  greater  or  less 
strength  to  the  welded  part,  and  for  this  reason  it  is  impossible 
to  draw  conclusions  from  the  work  of  one  operator  as  to  the  work 
of  another.  An  expert  in  aluminum  welding  is  distinguishable 
by  his  care  in  the  preparation  of  the  surfaces  to  be  welded; 
judgment  in  preheating  and  reheating  (or  annealing)  of  the  work; 
the  choice  of  a  well-constructed  torch;  the  determination  and 
maintenance  of  the  correct  proportions  of  oxygen  and  acetylene 
issuing  from  the  nozzle  of  the  torch;  in  the  entire  application 
of  the  system;  the  estimation  of  the  area  to  be  fused  in  each 
partial  operation;  the  manipulation  of  the  welding  flame  at 
the  right  moment  when  fusion  has  proceeded  so  far  that  com- 


WELDING  ALUMINUM  193 

plete  welding  is  assured;  the  dexterity  in  preventing  the  defor- 
mation of  the  metal  under  the  torch;  and  lastly,  the  rapidity  and 
ease  of  the  operation,  thereby  preventing  the  overheating  of  the 
metal  and  the  avoidance  of  damaged  welds.  Most  of  these  re- 
quirements, of  course,  apply  to  the  welding  of  other  metals  also. 
Examples  of  Aluminum  Welding.  —  Some  specimens  of 
welded  sheet  aluminum  are  shown  in  Fig.  4.  The  aluminum 
sheet  A  is  0.064  inch  thick  and  was  welded  by  a  beginner,  with 
the  oxy-acetylene  torch.  The  weld  B  has  a  good  appearance 


Fig.  8.   Aluminum  Inlet  Manifold  —  Repairs  Completed 

on  the  top  surface,  but  thorough  fusion  has  not  occurred.  Good 
welds  are  shown  at  C  and  D;  the  aluminum  sheet  C  is  0.048  inch 
thick,  and  Z>,  0.116  inch  thick.  The  flanged  weld  E  was  im- 
properly made;  thickness  of  aluminum,  0.048  inch.  The  flanged 
weld  F  was  properly  made  and  afterward  hammered. 

Welding  Aluminum-zinc  Alloys.  —  Alloys  of  aluminum  and 
zinc  present  much  the  same  difficulties  as  are  encountered  in 
welding  aluminum-copper  alloys.  These  alloys  are  now  exten- 
sively used  in  the  automobile,  aeronautical,  and  kindred  indus- 
tries where  strength  combined  with  lightness  is  a  necessity.  A 
typical  automobile  repair  job  is  shown  in  Fig.  5,  which  illus- 
trates the  crank-chamber  or  gear-case.  The  upper  view  shows 


194  WELDING  ALUMINUM 

the  fractured  gear-case,  whereas  the  lower  view  shows  the  same 
case  repaired  by  oxy-acetylene  welding. 

Feeding  Rods.  —  As  already  mentioned,  the  added  metal 
should  have  practically  the  same  composition  as  the  material 
being  welded.  The  necessary  alloys  of  aluminum  and  zinc  are 
not  always  as  readily  obtainable  as  feeders,  especially  in  the 
form  of  strips,  which  are  preferable,  so  that  many  operators  use 
pure  aluminum  during  the  welding  process.  However,  the  add- 
ing of  molten  metal  from  feeders  of  pure  aluminum  should  be 


Fig.  9.   Aluminum  Crankcase  showing  Method  of  Preventing  Cracks  in  Welding 

strictly  avoided;  thus,  if  an  alloy  containing,  say,  25  per  cent  of 
zinc,  is  being  welded,  its  melting  point  will  be  approximately  90 
degrees  F.  lower  than  that  of  the  aluminum  added,  the  result 
being  increased  difficulty  in  working  and  incoherency  of  the  parts 
rather  than  a  true  autogenous  weld.  At  the  same  time,  if  pure 
aluminum  is  used,  the  weld-zone  will  be  softer  and  more  flexible 
than  the  rest  of  the  work.  In  addition,  the  weld-zone,  if  too  soft, 
will  be  almost  certain  to  break  out  again,  and  it  is  essential  that 
the  added  metal  should  contain  a  percentage  of  zinc,  so  that  the 
weld-zone  will  have  a  hardness  approximately  equal  to  that  of  the 
rest  of  the  article.  The  conditions  as  stated  should  be  observed 


WELDING  ALUMINUM 


195 


as  nearly  as  possible,  if  a  true  autogenous  weld  is  desired.  It 
will  be  gathered  from  the  foregoing  that  perfect  welds  are  thus 
readily  attained  in  aluminum  and  the  aluminum-zinc  alloys  by 
those  having  adequate  knowledge  of  how  to  employ  this  new 
art  correctly. 

Difficulties  in  Welding  Aluminum-zinc  Alloys.  —  A  zinc  alloy 
is  generally  identified  by  the  condensation  of  the  white  zinc 
oxide  on  the  cooler  part  of  the  casting  during  welding,  and  it 
may  be  necessary  to  cut  or  break  the  casting  at  some  place 
where  it  can  be  repaired  without  bad  contraction  strains,  in  order 
that  the  weld  in  the  original  break  may  be  made.  It  is  not 
very  often  that  the  zinc  alloy  is  encountered  at  the  present 


Fig.  10.   Aluminum  Crankcase,  Defective  Part  used  for  Pattern  and 
New  Part  cast  from  Pattern 

time,  although,  when  it  is,  it  may  cause  the  welder  a  great  deal 
of  trouble,  and,  in  some  cases,  it  may  be  impossible  to  do  the 
work.  It  is  necessary  with  such  zinc  alloys  to  preheat  the  whole 
piece  to  as  high  a  temperature  as  is  safe,  and  handle  it  very  care- 
fully. Sometimes  it  is  advisable  to  have  an  extra  man  to  help 
in  handling  the  work,  for  if  the  piece  is  dropped  or  jarred  it  may 
be  damaged  considerably.  When  the  weld  is  rather  long,  it  is 
sometimes  necessary  to  use  two  welders,  beginning  at  the  center 
and  working  toward  both  ends,  so  that  the  variation  in  tempera- 
ture and  the  resulting  strains  are  not  so  great  as  they  would  be 
if  only  one  torch  were  used.  In  the  case  of  a  copper  alloy,  this 
brittleness  does  not  exist  to  so  great  an  extent,  and  it  is  not 
necessary  to  take  such  great  precautions,  but  in  all  cases  where 


196 


WELDING  ALUMINUM 


the  defect  extends  into  the  body  of  the  casting,  it  is  advis- 
able to  thoroughly  preheat  and  handle  it  carefully.    Aluminum 

oxidizes  readily,  particu- 
larly at  high  tempera- 
tures, and  as  the  oxide 
melts  at  a  much  higher 
temperature  than  the 
metal,  and  is  heavier 
than  the  melted  metal, 
it  is  likely  to  become 
mixed  into  the  melted 


Same  Crankcase  as  shown  in  Fig.  10 
—  Finished  Weld  on  Inside 


mass    and    produce    a 
poor  weld. 
The   Field  of 


Fig.  11. 

—  Finished   Weld    nn    Tnsido 

Alum- 
inum Welding.  —  One  of  the  widest  fields  for  the  products  of 
aluminum  sheet  welding  is  in  the  manufacture  of  large  metal 
vats  and  utensils  for 
brewing  and  industrial 
purposes.  Compared 
with  copper,  aluminum 
sheets  are  now  (1916) 
cheaper,  66  per  cent 
lighter,  and  less  readily 
attacked  by  organic 
acids.  Any  compounds 
formed  with  aluminum 
are  absolutely  non- 
poisonous  and  the  metal 
is  very  easily  cleaned. 
By  welding  and  hammer- 
ing the  joints,  the  walls 
of  brewing  vessels  are 
made  absolutely  flush 

Without  any  projections.       Fig.  12.   Same  Crankcase  as  shown  in  Fig.  10 

Brewing  vessels  are  con-  —Finished  Weld  on  Outside 

structed  up  to  25,000  gallons'  capacity,  using  aluminum  plates 
up  to  84  inches  or  more  in  width,  shaped  upon  bending  rolls. 


WELDING  ALUMINUM 


197 


The  majority  of  these  large  vessels  are  cylindrical  or  spherical, 
but  rectangular  vats  are  widely  used,  many  of  these  being  of 
wood,  lined  with  sheet  aluminum  welded  in  the  form  of  the  tank. 
Welding  is  also  necessary  for  the  production  of  tubular  distil- 
lation coils;  as  tubing  (particularly  in  the  larger  sizes)  can  only 
be  drawn  in  limited  lengths,  it  is  necessary  to  join  up  a  large 
number  of  pieces  to  form  a  tubular  coil  of  average  dimensions. 

A  further  important 
use  which  is  made  of  the 
oxy-acetylene  torch  is 
for  the  welding  of  auto- 
mobile bodies.  Many 
of  these,  particularly  of 
the  limousine  type,  are 
built  up  of  aluminum 
sheets,  the  sheets  being 
welded  so  as  to  secure 
an  absolutely  flush 
surface.  This,  however, 
is  only  one  of  the  many 
promising  fields  for  the 
autogenous  welding  of 
aluminum. 

Examples  of  Alumi- 
num Welding.  —  Fig.  6 
shows  the  best  method 


Fig.  13.   Example  of  Badly  Damaged  Aluminum 
Casting  which  has  been  welded 


of  replacing  a  broken  lug  on  an  aluminum  manifold.  It  should 
be  laid  on  the  table  as  shown,  and  a  small  weight  put  against 
the  lug  to  keep  it  from  moving.  No  larger  tip  should  be  used 
than  is  absolutely  necessary,  in  order  to  avoid  melting  the  lug, 
this  being  likely  to  occur  if  care  is  not  taken.  The  cold  table 
will  tend  to  overcome  part  of  this  trouble,  as  it  conducts  an 
excess  of  heat  away.  After  the  back  of  the  lug  is  welded  (and  the 
weld  should  be  made  almost  entirely  through  from  this  side),  the 
inside  should  be  finished,  being  careful  to  remove  all  the  crack. 
It  is  not  possible  in  the  case  of  lugs  on  aluminum  manifolds 
to  use  the  block  and  clamps  used  in  the  case  of  cast  iron,  as  alu- 


198 


WELDING  ALUMINUM 


minum  would  crush  under  the  clamping  strain.  Immediately 
after  welding,  the  lug  should  be  tested  with  a  straightedge  to 
be  sure  that  it  is  true  with  the  rest  of  the  face.  If  not,  it  can 
either  be  bent  down,  or  a  little  metal  added  where  it  is  low. 
In  the  majority  of  cases,  and  especially  in  the  case  of  small 
lugs,  it  does  not  pay  to  put  back  the  old  lug,  and  it  is  good  prac- 
tice to  build  up  a  new  one.  An  expert  welder  can  build  up  a  lug 
without  any  assistance  from  forms,  etc.,  but  the  beginner  had 

better  make  a  mold  out 
of  a  thin  piece  of  sheet 
metal,  of  the  height  and 
shape  of  the  lug,  and 
hold  it  in  place  with  a 
small  weight,  filling  up 
the  mold.  The  body  of 
the  manifold  should  be 
raised  about  ^V  mcn 
from  the  table  with  a 
piece  of  a  hacksaw  blade, 
or  something  similar,  to 
allow  stock  for  finishing. 
It  is  necessary  in  this 
case  to  be  particularly 
careful  to  secure  a  good 
union  between  the  new 
metal  and  the  old. 
Repairing  an  Inlet 


Fig.  14.    Opposite   Side  of   Aluminum   Casting 
shown  in  Fig.  13 


Manifold.  —  Figs.  7  and  8  show  the  best  method  for  repairing 
an  inlet  manifold.  The  original  manifold  was  cast  in  one  piece 
of  aluminum.  Later  it  was  desired  to  change  the  carburetor, 
and,  as  the  new  carburetor  flange  would  not  fit  the  manifold, 
a  new  flange  was  made  of  brass  and  screwed  on.  The  threads 
on  the  manifold  can  be  seen  distinctly.  The  repair  was  made 
by  casting  a  flange  of  aluminum,  using  the  old  brass  flange  as 
a  pattern  by  filling  up  in  places  to  permit  its  being  drawn 
from  the  sand,  and  welding  it  on.  The  finished  job  is  shown  in 
Fig.  8. 


WELDING   ALUMINUM  tQ() 

Replacing  Crankcase  Lugs.  —  Fig.  9  shows  a  type  of  crank- 
case  that  frequently  gives  trouble  from  the  lugs  breaking  off. 
Here  three  of  the  lugs  were  broken  when  the  case  was  received, 
and  the  shop  was  instructed  to  reinforce  the  others.  The  miss- 
ing lugs  were  C,  E,  and  F.  These  were  built  up  solid.  All  the 
others  were  reinforced  with  the  exception  of  B.  This  was  not 
done  because  of  the  desirability,  found  by  experience,  of  avoid- 


Fig.  15.   Broken  Aluminum  Transmission  Case 

ing  cracking  through  the  end  of  the  case,  which  generally  hap- 
pens, and,  inasmuch  as  all  of  the  other  lugs  for  both  pairs  of 
cylinders  were  heavy,  it  was  thought  unnecessary  to  reinforce 
lug  B.  No  precaution  with  which  the  author  is  acquainted  will 
invariably  stop  the  cracking  at  this  lug.  However,  in  the  ma- 
jority of  cases,  the  welding  of  the  lugs  at  C,  F,  etc.,  can  be  done 
without  cracking  the  sides,  provided  loose  wet  asbestos,  as  shown 
at  A ,  is  packed  so  as  to  cover  the  side,  and  is  allowed  to  become 


200 


WELDING  ALUMINUM 


dry  while  the  case  is  preheating.  This  keeps  the  heat  of  the 
welding  flame  from  striking  the  side  of  the  case  and  overheating 
it.  It  should  also  be  stated  that,  in  the  majority  of  cases  of  this 
kind,  the  material  appears  to  be  a  zinc  alloy,  which  is  very 
likely  to  crack  even  with  the  best  treatment.  The  foregoing 


Fig.  16.   Method  of  Saving  Bearings  and  Aligning  Parts  of 
Broken  Case 

method  of  overcoming  the  difficulty  can  be  frequently  applied 
to  other  cases. 

Repairing  a  Crankcase.  —  Figs.  10,  n,  and  12  show  an  alu- 
minum crankcase  of  an  old-style  automobile  motor,  which  is 
located  on  the  rear  axle  of  the  car.  The  part  removed  had  been 
at  some  time  soldered  in,  and  while  this  job  was  all  right  for  a 
while,  it  eventually  began  to  leak.  Another  crack  also  appeared 
which  made  it  necessary  to  repair  it  in  some  way.  As  it  would 
have  been  impossible  to  do  any  welding  in  the  presence  of  the 
solder,  the  entire  defective  piece  was  cut  out  and  used  as  a 


WELDING  ALUMINUM 


2OI 


pattern,  as  shown  at  A,  Fig.  10.  Enough  plaster-of-paris  was 
added  on  the  inside  and  face  of  the  piece  to  allow  for  finishing. 
The  casting  made  from  the  pattern  is  shown  at  B7  and  the 
finished  work  in  Figs,  n  and  12.  This  job  illustrates  the  possi- 
bility of  using  the  pieces  removed  as  patterns,  instead  of  making 
new  plaster-of-paris  patterns.  Even  when  the  parts  removed  are 
quite  badly  broken,  they  can  sometimes  be  fastened  together 


Fig.  17.   Outside  View  of  Completed  Repair  Job 

with  plaster-of-paris  much  more  easily  than  a  new  pattern 
could  be  made.  This  is  particularly  true  where  there  are  lugs 
or  other  projections  which  are  difficult  to  reproduce  in  plaster- 
of-paris.  A  little  ingenuity  will  frequently  reduce  the  time  on 
a  job  of  this  kind  considerably. 

Repairing  an  Aluminum  Housing.  —  Figs.  13  and  14  illus- 
trate what  can  be  done  with  a  badly  damaged  aluminum  casting. 
The  process  through  which  it  was  put  is  no  different  from  that 


2O2 


WELDING   ALUMINUM 


which  has  been  explained  before,  and  is  of  interest  principally 
on  account  of  the  fact  that  there  was  over  six  feet  of  cracks  in 
the  piece.  In  this  particular  case,  the  preheating  was  done  with 
two  Bunsen  burners  which  were  kept  lit  while  the  piece  was 
being  welded.  The  Bunsen  burners  were  used  on  account  of  the 
difficulty  of  handling  the  piece  in  the  fire.  While  it  is  generally 
unnecessary  to  use  a  helper  to  handle  a  piece  of  this  size,  in  this 


Fig.  18.   Inside  View  of  Welded  Case 

case,  on  account  of  the  location  of  the  breaks  and  the  large 
number  of  times  the  work  had  to  be  turned  over,  time  was 
saved  by  using  a  helper. 

Repairing  Aluminum  Transmission  Case.  —  Figs.  15  to  18 
show  a  badly  broken  aluminum  transmission  case  of  an  old 
design  with  babbitt  bearings.  It  is  quite  difficult  to  re-babbitt 
such  bearings  so  as  to  preserve  the  center  distances  between 
the  shafts,  unless  a  jig  is  available;  hence  it  was  decided  to 


WELDING  ALUMINUM 


203 


save  them.  The  width  of  the  face  of  the  crankshaft  jig  was 
just  right  to  permit  of  the  face  of  the  transmission  case  being 
laid  on  it  and  clamped  in  position  as  shown  in  Fig.  16.  This 
does  not  show,  however,  all  the  clamps  that  were  applied. 
The  two  clamps  shown  are  simply  to  hold  the  pieces  in  place 
while  the  photograph  was  taken.  The  first  operation  was  to  weld 


Fig.  19.  Upper  and  Lower  Halves  of  Crankcase  as  received  for  Repairs 

the  cracks  A,  B,  and  C  while  the  two  halves  were  separated. 
The  case  was  then  lined  up,  and,  in  order  to  prevent  uneven 
contraction,  two  welders  did  the  work,  beginning  at  the  hole  D 
in  the  center.  When  the  first  man  had  welded  about  2  inches 
on  his  side,  the  other  man  started  in,  and  they  finished  the  case  to- 
gether. The  result  was  complete  alignment  and  a  very  satisfac- 
tory job.  The  finished  work  is  shown  in  Figs.  17  and  18,  after  it 
had  been  rough-ground.  In  order  to  save  the  bearings,  they 


204 


WELDING  ALUMINUM 


Fig.  20.   Method  of  Clamping  Broken  Bearing  in  Place 


Fig.  21.  Aluminum  Crankcase  being  reheated 


WELDING  ALUMINUM  205 

were  filled  with  plaster-of-paris  as  shown  in  Fig.  15.  This  was 
allowed  to  dry  thoroughly,  and  was  then  warmed  over  a  gentle 
charcoal  fire  to  drive  out  the  moisture.  The  plaster-of-paris  was 
scraped  off  level  with  the  face  of  the  aluminum,  in  order  that  the 
cold  base  of  the  crankshaft  jig  might  come  into  as  close  contact 
as  possible  with  the  babbitt  and  thus  keep  it  cool  while  welding. 
Preheating  was  done  with  two  Bunsen  burners,  one  on  each 
side.  All  the  babbitt  was  saved,  except  the  small  corner  in  one 


Fig.  22.  End  Bearing  finished,  Center  Bearing  built  up,  and  Front 
Bolting  Lug  welded 

bearing,  as  shown  in  Fig.  18,  at  A.    The  alignment  of  the  bear- 
ings and  face  was  perfect. 

Repairing  Badly  Damaged  Crankcase.  —  Figs.  19  to  28  show 
that,  no  matter  how  bad  the  damage  may  appear,  it  is  possible 
to  repair  a  crankcase,  provided  a  little  ingenuity  is  used.  One 
of  the  frame  lugs  is  entirely  broken  off  and  another  cracked  on 
both  sides,  and  all  three  bearings  are  broken  out;  in  addition, 
most  of  the  end  of  the  bottom  half  is  missing.  This  damage 
was  caused  by  allowing  the  center  bearing  to  become  loose, 
which  caused  the  crankshaft  to  break  and  resulted  in  the  damage 
shown.  An  examination  of  the  crankcase  made  it  evident  that  it 
would  be  very  difficult  and  inadvisable  to  replace  the  pieces  of 
the  center  and  front-end  bearings.  At  the  time  Fig.  19  was 
photographed,  it  was  not  noticed  that  the  top-end  bearing  was 


206 


WELDING  ALUMINUM 


Fig.  23.  Upper  Half  of  Crankcase  as  shown  in  Fig.  22,  with  welding 
completed 


Fig.  24.   End  Bearing  partly  welded  in  and  Pieces  set  ready 
for  Welding 


WELDING   ALUMINUM 


207 


as  badly  broken  as  shown  in  Fig.  22,  although  it  was  known  to 
be  cracked.  The  first  operation  was  to  warm  the  crankcase 
in  a  rather  small  char- 
coal fire,  as  shown  in 
Fig.  21,  and  weld  the 
frame  lug  A,  Figs.  19, 
20,  and  21,  in  place, 
taking  care  to  put  it  in 
line  as  closely  as  pos- 
sible.  This  weld  is 
shown  at  J5,  Figs.  21 
and  22.  The  next  oper- 
ation was  to  set  the 
rear-end  bearing  C, 
Figs.  20,  21,  and  24,  in 
place,  clamping  it  as 


shown    in    Figs.    2O   and      FiS-  25<   Lower  Half  of  Crankcase  to  be  repaired 

21.    Planed  blocks  were  used  to  hold  it  true,  the  surfaces  of 
the  body  of  the  crankcase  on  which  these  blocks  rest  having 

been  previously  tested 
with  a  straightedge  to 
make  sure  that  they 
were  true.  It  is  gener- 
ally desirable  in  the  case 
of  a  crack  in  the  side 
or  end  of  a  crankcase  to 
do  all  the  welding  ex- 
cept one  crack,  and  then 
begin  with  one  end  of 
that  crack,  as  for  in- 
stance at  D,  Fig.  24, 
and  end  up  at  the  other 
end. 

In   this   case,   this   is 
not    advisable,    because 


Fig.  26.    Plaster-of-paris  Pattern  for  Missing 
Part  and  Rear-end  Bearing  Cap 


the  important  point  is  to  have  the  rear-end  bearing  accurately 
in  position,  and  this  can  be  done  better  by  setting  the  fractures 


208 


WELDING  ALUMINUM 


together,  than  would  have  been  possible  if  any  shrinkage  had 
taken  place  from  the  prior  welding-in  of  piece  E  and  filling  up 
at  F,  Fig.  24,  which  latter  part  was  missing.  It  is  evident  that 
it  would  have  been  difficult  to  make  the  bearing  straight  and 
true  under  these  conditions. 

In  Fig.  24,  when  welding  in  the  end  bearing,  the  two  side  welds 
were  not  finished  quite  up  to  the  ends  of  the  breaks  at  H  and  /. 
This  was  to  permit  of  an  easier  fitting  of  the  piece  E,  and  is  a 
practice  that  should  also  be  followed  where  several  pieces  have 

to  be  put  in  separately. 
It  might  be  stated  that 
the  end  bearing  fitted  in 
place  very  nicely,  as 
may  be  seen  from  Fig. 
20.  Piece  E  was  then 
welded  and  hole  F  filled 
up,  as  was  also  a  stud 
hole  in  boss  B,  Fig.  19. 
It  is  not  advisable  gen- 
erally to  attempt  to  pre- 
serve the  thread  in  a 
hole  through  which  a 
crack  runs.  The  job  is 
much  more  solid  if  it  is 
filled  up.  The  next  op- 
eration was  the  welding  of  the  center  bearing,  which,  as  explained 
above,  was  built  up  new.  Then  the  other  frame  lug  v/as  welded 
as  shown  in  Fig.  22,  and  finally  the  front-end  bearing  was  built 
up,  the  finished  job  being  shown  in  Fig.  23. 

Some  knowledge  of  the  shape  of  the  rear  end  of  the  bottom 
half  of  the  crankcase  was  needed  in  order  to  make  the  pattern 
shown  in  Fig.  25.  It  so  happened  that  the  welders  were  familiar 
with  what  had  to  be  done,  or  it  would  have  been  necessary  to 
examine  a  similar  part  in  good  condition.  The  bearing  cap  was 
put  in  place  on  the  upper  half  of  the  crankcase  and  used  as  a 
guide  in  the  preparation  of  the  pattern.  It  was  necessary  to 
remove  that  part  of  the  pattern  which  occupied  the  space  A, 


Fig.  27.   Lower  Half  of  Crankcase  shown  in 
Fig.  25,  as  repaired 


WELDING  ALUMINUM  209 

Fig.  25,  as,  if  it  had  been  left,  it  could  not  have  been  drawn  out 
of  the  sand.  Stock  was  allowed  for  finishing  at  D,  Fig.  25,  and 
B  and  C,  Fig.  26. 

Figs.  27  and  28  show  the  lower  half  of  the  crankcase  welded, 
while  Fig.  29  shows  both  halves  of  the  crankcase  machined  and 
ready  for  service,  except  for  the  drilling  and  tapping  of  the  holes 
for  the  center  and  front-end  bearing  cap  studs.  This  could  not 
be  done,  as  the  caps  were  not  at  hand. 

No  special  precautions  had  to  be  observed  in  welding  this 
case,  the  main  considerations  being  the  measuring  of  the  diam- 
eters of  the  bearings  before  doing  the  work,  as  no  two  of  them 


Fig.  28.   Inside  View  of  Repaired  Lower  Half  of  Crankcase 

are  the  same  size;  keeping  the  crankcase  quite  warm  while  doing 
the  work;  and  doing  it  as  quickly  as  possible,  which  is  a  necessity 
in  all  aluminum  welding.  Of  course,  the  machining  of  such  a 
job  requires  considerable  care  and  is  best  done,  as  far  as  the  bear- 
ings are  concerned,  in  a  horizontal  boring  machine.  If  this  tool 
is  not  at  hand,  it  can  be  done  in  a  lathe  by  clamping  the  case  on 
the  carriage  and  using  a  boring-bar  between  the  centers.  The 
job  can  be  done  in  one-half  the  time  or  less  on  a  horizontal  bor- 
ing machine,  as  it  can  be  set  up  with  greater  ease  and  accuracy. 
The  cylinder  face  of  the  upper  half  was  milled  off  at  the  weld, 
but  it  was  not  found  necessary  to  bore  the  rear-end  bearing,  nor 
to  mill  off  any  of  the  faces  of  the  crankcase,  except  where  stock 


2IO 


WELDING  ALUMINUM 


had  been  allowed  for  the  purpose,  or  where  the  welds  had  been 
made;  so  that  it  is  perfectly  possible,  by  taking  due  care,  to 
avoid  much  of  the  machine  work  that  is  frequently  done. 

This  example  of  welding  is  given  in  considerable  detail,  be- 
cause it  covers  a  great  number  of  instances  which  do  not  have  all 
of  the  different  kinds  of  damage  sustained  by  this  one.  It  was 


Fig.  29.   Both  Halves  of  Crankcase  Machined  and  Ready  for  Assembling 

not  a  particularly  difficult  job,  although  considerable  time  was 
consumed  in  doing  it.  The  comparative  simplicity  is  largely 
accounted  for  by  the  fact  that  there  was  no  trouble  from  contrac- 
tion, the  damage  being  so  great  that  the  strains  were  easily  taken 
care  of. 

Aluminum    Castings    for    Repair    Work.  —  It  might  be  well 
to  mention  here  the  necessity  of  obtaining  good  castings  for  such 


WELDING   ALUMINUM  211 

repair  work.  It  will  not  do  to  use  the  material  frequently  fur- 
nished by  small  foundries,  which  they  claim  to  be  aluminum. 
The  author  uses  nothing  but  No.  12  metal,  which  can  be  pur- 
chased from  aluminum  manufacturers  in  pigs.  No  scrap  what- 
ever is  permitted,  nor  any  other  alloy.  In  case  of  serious 
difficulty  in  obtaining  castings  of  the  proper  quality,  or  if  it 
should  be  necessary  to  send  a  long  distance  for  them,  it  is  recom- 
mended that  a  small  crucible  be  obtained  and  pig  metal  melted 
in  it  in  a  small  furnace  designed  for  the  purpose.  This  furnace  can 
be  connected  with  any  flue  ordinarily  used  in  a  stove.  It  is  not 
satisfactory  to  melt  this  metal  in  an  iron  ladle,  as  it  is  too  much 
exposed  to  the  action  of  the  air.  As  soon  as  the  metal  is  melted, 
it  should  be  covered  with  a  layer  of  fine  charcoal  to  prevent 
oxidation  as  much  as  possible.  A  small  flask  made  of  wood  and 
some  fine  molding  sand  are  easily  obtained,  and  will  be  found 
very  convenient  for  many  purposes. 

Care  should  be  taken  in  melting  aluminum  not  to  allow  it 
to  become  too  hot,  and  it  should  be  well  skimmed  while  pouring 
to  prevent  the  oxide  from  passing  into  the  mold.  The  shrink- 
age of  aluminum  is  considerable,  about  3%  inch  per  foot,  and  the 
pattern  should  be  well  rapped  in  order  to  allow  for  this,  or  else 
the  necessary  stock  should  be  added  to  the  pattern  to  take 
care  of  it.  A  beginner  will  probably  have  some  trouble  at  the 
start,  but  a  little  care,  and  if  possible,  the  observation  of  the 
various  processes  at  some  foundry,  will  help  a  great  deal.  A 
greater  amount  of  pig  metal  should  be  melted  than  is  needed 
for  the  casting,  and  any  surplus  should  be  poured  into  a  mold 
or  into  a  hollow  made  in  the  sand  pile,  and  not  left  in  the  crucible. 


CHAPTER  VIII 
SHEET  METAL,  BOILER,  PIPE,  AND  TUBE  WELDING 

SHEET  metal  is  used  in  so  many  different  forms  and  for  such 
a  variety  of  purposes  that  it  is  impossible  to  give  any  specific 
directions  that  will  cover  all  cases,  in  regard  to  the  methods  to  be 
followed  in  welding  it.  However,  some  general  points  can  be 
noted,  and  the  application  to  specific  cases  can  often  be  derived 
from  them.  It  should  never  be  forgotten  that  in  any  welded 
piece  there  are  strains  due  to  contraction  and  expansion  caused 
by  the  heating.  In  the  case  of  brittle  metals,  such  as  cast  iron, 
this  strain  will  probably  manifest  itself  by  the  piece  cracking  at 
some  time  during  the  operation  or  afterward.  In  the  case  of 
tougher  metals,  such  as  steel,  the  strain  may  not  and  probably 
will  not  so  manifest  itself,  but  it  will  be  found  instead  that  the 
piece  will  become  distorted.  The  same  general  principles  for 
taking  care  of  strains  in  brittle  metals  apply  in  the  case  of  tough 
metals.  In  other  words,  contraction  must  be  allowed  for  in 
some  way,  either  by  preheating,  separating  the  parts,  or  by  ex- 
panding some  part  of  the  piece  by  heat  or  power,  etc. 

Warping  due  to  Heating  of  Plates.  —  If  a  piece  of  steel 
plate  J  inch  thick  and  6  inches  square 'be  heated  red-hot  in  the 
center  with  a  torch,  no  particular  change  will  be  noticed  during 
the  heating,  but  on  cooling  off,  while  no  crack  will  occur  as  it 
would  if  the  plate  were  made  from  cast  iron,  the  sheet  will  be- 
come badly  warped.  This  warping  can  be  remedied,  as  is  done 
in  everyday  practice  in  boiler  or  tank  shops,  by  laying  the  plate 
on  an  anvil  or  solid  block  of  iron  and  peening  it  with  a  hammer 
until  it  is  straight.  This  is  an  operation  that  requires  consid- 
erable skill  and  experience,  and  is  brought  to  its  highest  develop- 
ment in  the  case  of  large  circular  and  band  saws  used  for  cutting 
wood.  These  have  to  be  "hammered"  to  suit  the  speed  at 
which  they  run  and  the  conditions  under  which  they  operate. 


WELDING   SHEET   METAL  213 

Without  some  experience,  an  attempt  to  straighten  such  a  piece 
of  steel  will  result  in  making  it  worse  than  it  was  originally,  and 
while  this  process  can  be  used,  it  is  desirable  to  avoid  it,  if  pos- 
sible. In  the  case  of  a  small  sheet,  much  of  the  difficulty  can  be 
overcome  by  heating  it  red-hot  before  welding,  but,  in  the  case 
of  a  large  sheet,  this  practice  is  not  feasible,  and  it  is  generally 
difficult,  if  not  impossible,  to  weld  it  neatly  at  the  center.  How- 
ever, it  is  seldom  necessary  to  make  such  an  attempt,  the  major- 
ity of  sheet  welding  being  done  along  the  edges,  or  in  other 
places  where  the  expansion  due  to  the  heating  can  be  more  readily 
controlled. 

Welding  Thin  Sheet  Steel.  —  The  welding  together  of  short 
pieces  of  thin  steel  may  be  frequently  accomplished  by  pre- 
heating the  whole  piece  along  the  edges  to  be  welded.  If 
there  are  many  pieces  of  one  kind  to  do,  it  will  pay  to  make 
an  arrangement  by  which  a  gas  burner  can  be  kept  under  the 
weld  while  it  is  made.  In  such  cases,  the  weld  may  be  " tacked'' 
(joined  by  an  autogenous  spot  weld)  at  several  points  along 
the  edges,  and  if  it  is  kept  red-hot  by  the  gas  flame  it  will 
give  very  little  trouble,  and  in  many  cases  the  distortion  will  not 
be  sufficient  to  cause  any  difficulty.  On  the  other  hand,  in  re- 
pair shops,  it  is  not  often  that  many  pieces  of  one  kind  are 
done,  it  being  generally  odd  jobs  that  are  received.  In  cases 
where  the  weld  is  long,  the  best  plan  is  to  separate  the  sheets 
at  one  end  by  an  amount  equal  to  about  i\  per  cent  of  their 
length,  and  bring  them  together  at  the  other  end.  If  it  is  found 
that  the  contraction  of  the  weld  pulls  the  sheets  together  too 
fast,  it  will  be  necessary  to  hold  them  apart  by  clamping,  wedg- 
ing, or  some  other  method,  forcing  the  contraction  to  take  place 
in  the  weld  rather  than  allowing  the  sheets  to  be  pulled  together. 
If,  on  the  other  hand,  the  sheets  do  not  come  together  fast 
enough,  stopping  the  welding  process  for  a  short  time  will  gen- 
erally correct  the  trouble,  as  the  sheets  cool  off  and  do  not  again 
regain  the  same  amount  of  heat. 

It  is  not  possible  to  clamp  thin  sheets  so  tightly  that  the 
edges  may  be  brought  absolutely  together  and  all  the  contrac- 
tion forced  to  take  place  in  the  weld.  Even  with  very  powerful 


214  WELDING  SHEET  METAL 

clamps  it  is  practically  impossible  to  obtain  the  same  pressure 
at  all  points  along  the  edges,  and  where  the  pressure  is  less, 
the  contraction  will  be  greater,  the  result  being  a  buckling  of  the 
sheet  and  a  wavy  appearance  on  finishing  the  job.  One  of  the 
easiest  ways  on  odd  jobs  of  this  kind  is  to  put  a  cross  of  ^-inch 
round  metal  between  the  sheets  a  considerable  distance  ahead 
of  the  torch,  advancing  it  or  moving  it  back  from  time  to  time 
as  the  contraction  of  the  weld  warrants.  This  has  its  limitations, 
because,  when  the  sheet  is  very  thin,  it  will  bend  rather  than  force 
the  contraction  to  take  place  in  the  weld;  but  if  the  sheets 
are  |  inch  thick  or  more,  it  is  very  satisfactory,  particularly  if 
clamps  are  placed  across  the  sheet  in  several  places,  to  keep  the 
edges  in  line  vertically.  Another  objection  to  the  use  of  clamps 
is  that,  unless  carefully  designed,  it  is  impossible  to  obtain  the 
same  pressure  on  the  sheets  twice  in  succession,  and  if  it  is  found 
that  a  certain  pressure  with  a  certain  amount  of  opening  at  one 
end  will  answer  the  purpose,  it  is  evident  that  less  pressure  will 
cause  the  sheets  to  come  together  too  fast,  and  vice  versa. 

In  the  case  of  very  thin  material,  such  as  is  used  for  steel  doors 
in  railway  passenger  equipment,  many  ingenious  jigs  and  clamps 
have  been  devised  to  hold  the  parts  absolutely  in  line  while 
welding.  They  all  operate  on  the  principle  of  forcing  the  con- 
traction to  take  place  in  the  weld.  As  they  are  special  for  each 
type  of  door  manufactured,  and  as  they  are  too  expensive  and 
generally  not  applicable  for  repair  welding  shops,  no  attempt 
is  made  to  give  any  details  of  their  construction,  it  being  suffi- 
cient to  say  that  the  results  obtained  by  their  use  are  exceedingly 
satisfactory,  and  good  results  could  not  be  obtained  without 
them. 

The  methods  outlined  are  applicable  not  only  to  flat  sheets, 
but  also  to  longitudinal  seams  of  tanks  such  as  range  boilers, 
oil  barrels,  etc.  In  many  cases,  automatic  welding  machines 
have  displaced  hand  work  on  such  articles  and  give  a  regularity 
of  welding,  uniform  quality  and  appearance  that  is  not  obtained 
by  hand  welding.  Light  sheet  welding  by  hand  is  really  a  spe- 
cial trade.  The  welder  must  have  a  steady  hand  and  must  keep 
in  continual  practice.  While  such  welds  made  by  an  ordinary 


WELDING   SHEET   METAL 


215 


welder  would  appear  to  him  very  regular  and  uniform,  they 
would  seem  to  the  expert  sheet  welder  rather  rough  and  irregu- 
lar, although  they  might  be  perfectly  sound.  Such  welds,  if 
properly  made,  require  very  little  finishing  and  result  in  as 
smooth  a  surface  after  grinding  as  the  original  sheet,  and  also 
have  no  buckling  or  other  defects.  The  thicker  the  sheet  is,  the 
less  is  the  trouble  from  buckling,  and  it  is  generally  possible 
to  make  a  nice  appearing  and  sound  weld  in  such  sheets  by 
keeping  the  wedge  of  metal  between  the  sheets  some  distance 
ahead  of  the  torch,  as  previously  explained. 

Speed  of  Sheet  and  Plate  Welding.  —  The  following  table 
shows  the  speed  at  which  the  welding  of  steel  and  iron  plates 
can  be  carried  out,  and  also  the  approximate  acetylene  consump- 
tion; this  table  is  furnished  by  the  Davis-Bournonville  Co. 


Thickness  of 
Metal,  Inch 

Feet  Welded 
Per  Hour 

Acetylene,  Per 
Hour,  Cubic  Feet 

Thickness  of 
Metal,  Inch 

Feet  Welded 
Per  Hour 

Acetylene,  Per 
Hour,  Cubic  Feet 

A 

30 

3.25 

A 

9 

18 

TV 

25 

5.00 

i 

4 

6 

25 

A 

2O 

8.25 

f 

4 

42 

i 

15 

I2.OO 

| 

3 

60 

The  oxygen  consumption  will  be  i.i  to  1.5  times  the  acety- 
lene consumption,  depending  upon  the  quality  of  the  blowpipe 
employed.  As  would  be  expected,  the  gas  consumption  per 
foot  of  work  increases  more  rapidly  than  the  thickness  for  all 
except  the  very  thinnest  material,  and  the  speed  at  which  the 
work  can  be  done  decreases  in  about  the  same  ratio  as  the  thick- 
ness increases.  On  the  basis  of  the  figures  given  in  the  table, 
it  has  been  stated  that,  for  constructional  work,  f -inch  metal  is 
about  as  thick  as  should  be  worked  with  the  oxy-acetylene  weld- 
ing method,  except  in  cases  where  older  methods,  such  as  rivet- 
ing, are  impossible.  For  repair  work,  the  case  is  altogether 
different;  metal  of  any  thickness  can  be  worked,  and,  in  almost 
all  cases,  the  repairs  effected  will  be  made  more  quickly,  better, 
and  more  economically,  than  by  the  older  methods.  As  re- 
gards constructional  work,  the  conclusion  that  a  f-inch  thick- 
ness constitutes  the  limit  of  the  metal  that  can  be  economically 


216 


WELDING  SHEET  METAL 


welded  is  somewhat  too  sweeping,  however,  as  this  depends  en- 
tirely upon  the  conditions;  and,  at  the  present  time,  there  is  a 
great  deal  of  new  work  done  on  sheets  f  inch  thick  and  over. 
The  considerations  which  influence  the  selection  of  the  method 
of  joining  thick  sheets,  aside  from  cost,  are  smoothness,  tight- 
ness of  the  joint,  the  pressure  to  which  the  joint  will  be  exposed 
in  service,  the  stresses  in  the  parts  welded,  and  a  number  of 
other  things  suggested  by  the  circumstances.  These  conditions 
all  have  an  important  bearing  upon  the  selection  of  the  method, 


JOINT  FOR 
LIGHT  PRESSURES 


Machinery 


Fig.  1.   Methods  of  Making  Joints  for  Heavy  and  Light  Pressures 

and  must  be  considered  in  repair  work  as  well  as  in  manufac- 
turing. 

Welding  Copper  and  Aluminum  Sheets.  —  The  welding  of 
sheets  of  flat  metals  other  than  steel  is  only  done  in  exceptional 
cases,  and,  while  the  same  principles  apply,  other  metals  are 
generally  more  ductile,  and  the  strain  can  be  more  readily 
taken  care  of.  It  should  not  be  forgotten  that  all  such  welds 
are  castings,  and,  except  in  the  case  of  aluminum,  the  weld  will 
not  be  as  strong,  nor  can  it  be  hammered  or  otherwise  worked 
as  safely  «as  the  original  sheet.  Pure  rolled  sheet  aluminum  or 
aluminum  sheet  with  but  little  alloy  can  be  welded  with  excel- 
lent results,  if  a  satisfactory  flux  is  used,  and  the  resulting  weld 


BOILER  WELDING  217 

will  be  as  malleable  as  the  original  sheet.  Such  work  is  done 
every  day  in  the  case  of  carriage  and  automobile  bodies,  and  the 
metal  is  afterward  beaten  over  the  forms  without  any  difficulty. 
In  the  case  of  copper  and  brass,  proper  annealing  will  help  the 
brittleness  of  the  weld  very  much,  but  this  cannot  always  be 
done,  and,  therefore,  care  should  be  exercised  in  subjecting  the 
weld  to  hammering,  rolling,  etc. 

Welding  Heads  of  Tanks.  —  In  the  manufacture  of  steel 
tanks,  there  is  no  special  difficulty  in  welding  in  the  heads. 
There  are,  however,  a  number  of  precautions  that  should  be 
observed  in  the  preparation  of  the  pieces,  the  principal  one  of 
which  is  that  they  should  be  so  designed  as  to  avoid  anything 
except  tensile  strain  in  the  weld;  that  is,  no  design  should  be 
made  in  which  there  is  any  chance  of  a  bending  strain  occur- 
ring, due  to  internal  or  external  pressure.  When  the  pressure 
is  very  low,  this  rule  may,  of  course,  be  disregarded.  Two  ex- 
amples are  given  in  Fig.  i,  showing  good  construction,  and,  as 
these  are  economical  as  well  as  safe,  it  is  not  necessary  to  show 
examples  of  objectionable  ones,  it  being  safe  to  assume  that  con- 
structions other  than  those  shown  will  not  give  as  good  results. 
There  are  two  principles  to  be  followed  in  making  such  joints: 
i.  That  the  included  angle  of  the  V  should  be  at  least  90  de- 
grees. 2.  That  the  sum  of  the  edges  of  the  V  should  be  as 
short  as  possible.  Modifications  of  these  principles  may  be 
allowable  in  special  cases,  but,  for  all  ordinary  work,  they  should 
be  strictly  followed.  In  making  any  welds  in  tanks  subjected  to 
pressure,  care  must  be  taken  to  have  the  weld  made  entirely 
through  the  sheet,  so  that  there  is  no  crack  or  remnant  of  the 
original  edges  of  the  sheet  left  unjoined.  This  subject  is  treated 
in  greater  detail  in  the  next  chapter. 

Boiler  Welding.  — The  welding  of  boiler  sheets  is  a  specialty, 
and  should  not,  except  in  the  simplest  cases,  be  undertaken  by 
a  repair  shop,  unless  the  welder  or  the  person  in  charge  is  thor- 
oughly familiar  with  boiler  construction  and  the  ordinary  repair 
methods.  So  much  depends  upon  the  soundness  of  a  boiler  that 
only  the  very  best  work  is  justifiable.  Such  work  can  only  be 
obtained  from  a  thoroughly  honest,  competent  welder,  who  will 


2l8  BOILER   WELDING 

at  all  times  do  the  best  that  lies  in  his  power.  Sound  welds,  free 
from  burnt  and  oxidized  spots  and  slag,  cannot  be  obtained, 
even  by  the  best  welder,  without  a  good  torch.  It  is  also  almost 
necessary  that  the  person  in  charge  of  the  shop  be  familiar  with 
boiler  construction  and  repairs. 

For  these  reasons,  Henry  Cave  has  proposed  what  he  calls 
the  "  three  license  system,"  for  boiler  welding,  by  which  the 
proper  authorities  would  license  the  plant  doing  the  work,  the 
apparatus  to  be  used,  and  the  men  actually  doing  the  work 
after  proper  examinations  and  tests  had  been  made.  There 
is  much  to  commend  this  plan,  although  the  details  would  have 
to  be  worked  out  carefully.  It  would  appear  that  if  those  in 
charge  of  the  operation  of  boilers  are  compelled  to  obtain  a 
license  for  the  protection  of  the  public,  those  making  repairs 
should  also  be  compelled  to  adopt  similar  "  safety-first "  methods. 
The  author  believes  that,  in  addition,  the  moral  character  of 
the  welder  should  be  carefully  looked  into,  as  all  the  welder's 
faculties  must  be  on  the  alert. 

For  such  shops  as  are  equipped  to  do  this  kind  of  work,  the 
rules  of  the  Federal  government  in  connection  with  marine 
inspection  are  an  excellent  guide  as  to  what  may  be  undertaken 
in  the  present  state  of  the  art.  These  rules  are,  of  course,  con- 
servative and,  in  the  case  of  marine  work,  must  be  closely  fol- 
lowed. The  Federal  rules  are  given  in  the  "General  Rules  and 
Regulations  prescribed  by  the  Board  of  Supervising  Inspec- 
tors," copies  of  which  may  be  obtained  at  any  of  the  local  offices 
of  the  Inspection  Department,  or  from  the  Department  of  Com- 
merce at  Washington,  D.C. 

The  boiler  insurance  companies  must  be  consulted  about  the 
work  contemplated  in  all  cases  when  insurance  is  carried,  as 
their  inspectors  would  reject  it  unless  the  work  met  with  their 
approval,  and  the  insurance  would  lapse.  As  a  matter  of  self- 
protection,  a  repair  shop  should  be  cautious  about  boiler  weld- 
ing, because  if  anything  happened  later  to  the  boiler,  even  though 
it  were  not  the  fault  of  the  welding,  serious  injury  might  result 
to  the  reputation  of  the  shop  doing  the  work.  On  the  continent 
of  Europe,  much  greater  progress  has  been  made  in  the  welding 


BOILER  WELDING  219 

of  boilers  than  in  the  United  States,  and  much  work  is  done 
there  that  is  not  yet  permitted  here.  Hence,  there  is  a  vast 
field  open  to  those  who  are  willing  to  take  the  time  and  make 
the  effort  to  become  accomplished  welders  in  this  line. 

The  technique  of  boiler  welding,  except  in  the  case  of  a  few 
specialists,  is  not  yet  developed  to  the  point  where  anyone 
except  such  specialists  should  make  welds  in  sheets  where  the 
working  stress  is  entirely  tensile,  such  as  the  shell  of  any  boiler  or 
the  roof  sheet  of  a  locomotive  type  boiler.  The  Interstate  Com- 
merce Commission  prohibits  such  welding  in  locomotive  boilers 
and  with  good  reason,  as  a  defective  weld  in  such  a  location 
would,  in  all  probability,  result  disastrously.  Nothing  about 
a  boiler  should  be  welded  unless  the  result  will  be  perfectly 
safe. 

There  is  probably  no  other  important  mechanical  structure 
in  which  more  accurate  knowledge  exists  as  to  the  actual  stresses 
involved,  and  as  to  the  strength  of  the  various  joints  used,  than 
a  boiler.  This  knowledge,  however,  is  unfortunately  not  as 
widely  disseminated  as  it  should  be,  and  the  lack  of  it  (and  in 
some  cases  the  desire  to  build  boilers  as  cheaply  as  possible)  has 
resulted  in  construction  that  is  not  good  and  is  sometimes  dan- 
gerous. These  cases  are  not  so  common  as  they  used  to  be, 
with  the  result  that  modern  boilers  generally  give  little  trouble 
from  defects,  unless  they  are  badly  treated,  or  carelessly  re- 
paired. The  chance  of  being  called  on  to  make  repairs  to  a 
boiler,  therefore,  is  generally  in  the  case  of  one  that  is  rather 
old.  Under  these  conditions,  the  author  always  makes  a  care- 
ful examination  and  if  he  thinks  the  boiler  is  unsafe,  he  refuses 
to  do  any  welding  at  all  on  it.  It  is  a  safe  plan  for  the  owner  of 
a  defective  boiler  to  have  it  inspected  by  one  of  the  boiler  in- 
surance companies;  and  if  they  will  insure  it  after  the  welding 
is  done,  of  course  the  work  can  be  proceeded  with.  If  they  will 
not  insure  it,  the  repairs  should  not  be  done. 

Simple  Boiler  Repairs.  —  There  are  a  number  of  simple  boiler 
repairs  that  can  be  readily  made,  in  which  the  strength  of  the 
boiler  is  not  particularly  involved,  such  as  welding  flue-sheet 
bridges,  fire  cracks  in  seams  from  the  rivet  holes  to  the  edge 


220  BOILER   WELDING 

of  the  sheet,  etc.  In  all  cases,  a  V  should  be  made  entirely 
through  the  sheet,  leaving  the  bottom  of  the  V  open  at  least  Ye 
inch,  so  that  the  metal  can  be  welded  from  the  bottom  up.  The 
dirt  and  scale  should  be  well  cleaned  off  the  inside  of  the  sheet 
as  well  as  the  outside.  It  should  not  be  forgotten  that  lime  or 
any  similar  form  of  scale  tends  to  make  a  brittle  weld.  Where 
one  sheet  laps  over  another,  as  in  the  case  of  a  fire  crack  in  a 
seam,  the  edges  of  the  crack  should  be  raised  after  beveling  by 
heating  somewhat  with  the  torch  and  driving  a  chisel  under- 
neath. This  permits  of  the  weld  being  made  entirely  through 
the  sheet.  In  taking  care  of  the  contraction  after  such  work, 
great  reliance  can  be  placed  on  hammering  of  the  weld  just  after 
it  is  made  so  as  to  expand  it.  The  hammering  must  not  be 
continued  too  long,  that  is,  below  a  blue  heat,  or  the  tendency 
will  be  to  produce  a  crack. 

Fire  cracks  and  broken  flue-sheet  bridges  mean  short  welds, 
and  there  is  very  little  chance  of  leaving  a  strain  in  those  cases. 
Where  the  weld  is  longer,  much  judgment  must  be  used  in  ham- 
mering, to  avoid  producing  serious  strains  which  may  later  re- 
sult in  cracking  the  sheet.  Again,  there  are  cases  where  sheets 
are  corroded  in  spots.  These  can  generally  be  built  up  with 
perfect  safety  and  to  good  advantage.  Frequently  an  expen- 
sive replacement  may  be  avoided  by  doing  this.  However,  in 
such  cases,  there  will  undoubtedly  be  a  loosening  of  the  rivets  if 
there  are  any  in  the  vicinity  of  the  work,  and  these  will  have 
to  be  replaced  or  calked  to  overcome  leaks.  In  some  cases,  it 
pays  to  cut  out  the  rivets  and  redrive  them  after  the  welding 
is  done.  Another  frequent  and  rather  easy  repair  is  the  adding 
of  sufficient  metal  to  a  worn  calking  edge  to  permit  of  the  sheet 
being  recalked.  This  can  easily  be  done  without  welding  to  the 
sheet  underneath.  After  the  welding  is  done,  the  metal  may 
be  hammered  down  and  chipped  and  calked  as  in  the  original 
construction.  A  small  patch  can  be  applied  in  the  corner  of  a 
firebox  quite  readily,  but  the  rivets  should  be  removed  for  a 
distance  of  8  or  10  inches  to  allow  for  contraction. 

In  a  general  way,  there  is  but  little  difficulty  from  contrac- 
tion in  welding  where  there  is  a  change  of  direction  in  the  sur- 


BOILER  WELDING  221 

face  of  the  sheet,  for  example,  near  a  flange  or  similar  bend, 
because,  by  removing  a  few  of  the  rivets,  the  contraction  takes 
care  of  itself  and  the  rivets  can  generally  be  replaced  easily. 
However,  in  the  case  of  a  flat  sheet,  the  problem  is  entirely 
different.  The  welding  of  cracks  in  boiler  furnaces  or  fireboxes 
requires  a  high  degree  of  skill  and  knowledge,  and  generally 
necessitates  the  use  of  special  appliances  for  confining  the  heat 
to  a  narrow  zone.  Such  cracks  do  not  develop  singly,  but  are 
accompanied  by  parallel  cracks  for  quite  a  distance  along  the 
sheet.  These  are  frequent  in  locomotive  boilers,  and  are  due  to 
the  fact  that  under  severe  service  the  water  is  driven  away  from 
the  sheets  so  that  they  become  overheated.  When  they  are 
hot,  the  pressure  in  the  boiler  tends  to  bulge  them,  causing 
cracks  to  appear  on  the  fire  side  between  the  vertical  rows  of 
staybolts,  and  on  the  water  side  through  the  centers  of  the  stay- 
bolt  holes.  In  the  course  of  time,  one  of  these  cracks  goes  through 
and  begins  to  leak.  While  there  may  be  no  evidence  of  any  more 
cracks,  the  bulging  of  the  sheet  indicates  that  there  are  at  least 
incipient  cracks  besides  the  one  giving  the  trouble.  Now  if  the 
leaky  crack  be  welded,  the  shrinkage  of  the  weld  will  open  up 
one  of  the  cracks  somewhere  in  the  vicinity,  the  weld  being 
stronger  than  the  rest  of  the  sheets. 

An  instance  has  been  cited  where  a  large  number  of  cracks 
of  this  kind  were  welded  in  one  firebox,  the  result  being  that 
finally  there  was  a  considerable  gap  in  the  last  crack  that  de- 
veloped, this  being  approximately  equal  to  the  sum  of  the  shrink- 
ages of  the  welds.  In  such  a  case  it  may  be  possible  to  weld  a 
crack,  but  the  author  does  not  believe  it  advisable  except  for 
temporary  purposes,  and  then  with  the  distinct  understanding 
that  the  job  is  not  sound  and  further  trouble  will  undoubtedly 
result.  In  order  to  take  care  of  the  contraction,  it  is  sometimes 
the  practice  to  run  streams  of  water  or  compressed  air  on  the 
sheet  on  each  side  of  the  crack,  about  4  inches  from  it,  thus 
preventing,  to  a  large  extent,  the  expansion  due  to  the  heat  of 
the  torch  and  reducing  the  contraction. 

The  highest  development  of  the  welder's  art  is  needed  in  the 
application  of  patches  in  the  center  of  a  stayed  surface,  such  as 


222  BOILER   WELDING 

a  side  or  flue-sheet  of  a  locomotive  firebox.  There  is  no  particu- 
lar difficulty  about  welding  the  first  side  or  even  the  second,  but 
the  trouble  comes  on  the  third  and  fourth,  particularly  on  the 
last  one.  It  is  always  necessary  to  use  a  box  patch,  that  is,  one 
that  is  dished  in  the  center,  so  that  the  dishing  will  take  the 
strain.  Such  work,  as  well  as  the  application  of  entire  side 
sheets,  and  patches  12  feet  long  in  large  fireboxes,  are  perfectly 
possible,  and  in  fact  are  done  every  day  in  locomotive  boiler 
shops,  but  they  are  the  work  of  men  who  are  trained  in  that 
direction,  and  they  should  never  be  done  by  any  ordinary  weld- 
ing shop.  It  is,  therefore,  unnecessary  to  give  any  detailed  de- 
scription as  to  how  this  work  should  be  attacked,  particularly  as 
the  appliances  for  doing  it  are  special,  and  have  to  be  modified 
to  suit  each  case.  There  is  one  thing,  however,  that  should 
always  be  done  in  case  of  any  work  inside  a  boiler,  or  other  con- 
fined space.  An  extra  man  should  be  stationed  at  the  tanks, 
which  should  always  be  kept  outside  of  the  space  or  boiler,  so 
that,  in  case  the  hose  bursts  and  the  acetylene  catches  fire,  it 
can  immediately  be  shut  off,  thus  avoiding  possible  fatal  injury 
to  the  men  inside. 

Welding  Galvanized  Plates.  —  In  the  welding  of  galvanized 
plates,  several  difficulties  are  met  with.  The  flame  in  contact 
with  the  zinc-covered  plate  produces  vapors  and  fumes  of  a 
nature  which  may  seriously  affect  the  health  of  the  welder. 
The  welds  are  also  liable  to  contain  impurities  —  zinc  and  slag 
—  and  as  the  soundness  of  the  weld  is  directly  dependent  upon 
the  amount  of  slag  and  zinc,  it  is,  therefore,  necessary  to  remove 
the  zinc  from  the  vicinity  of  the  weld  before  welding.  The  zinc 
should  be  entirely  removed  for  a  distance  of  from  i  to  if  inch 
on  either  side  of  the  central  line  of  the  weld,  and  as  the  zinc 
has  penetrated  the  steel  to  some  extent,  some  of  the  steel  will 
have  to  be  removed  also.  This  preparation  makes  the  cost 
of  the  weld  higher,  and  is,  therefore,  often  neglected,  but  a  strong 
joint  cannot  be  produced  in  any  other  way,  and  the  effect  on 
the  workman's  health  is  detrimental  if  the  preparation  is 
omitted.  If  the  plates  are  thicker  than  J  inch,  they  should  be 
beveled  in  order  to  produce  a  good  weld.  The  welding-rod 


TUBE   WELDING 


223 


should  be  of  Swedish  iron  of  suitable  dimensions  for  the  thick- 
ness of  the  plate  to  be  welded. 

Welding  Tin  Plate.  —  In  the  oxy-acetylene  welding  of  tin 
plate,  tin  is  not  eliminated  as  a  vapor  or  oxidized,  as  in  the  case 
of  zinc-coated  metal,  but  as  the  tin  is  absorbed  by  the  iron, 
when  the  latter  reaches  a  red  heat,  an  iron-tin  alloy  is  added  to 
the  molten  mass  of  metal,  and  the  weld  consists  of  very  large 
crystals  separated  by  numerous  fissures  and  cracks.  It  is,  there- 


Fig.  2.   Tube-rolling  Machine  built  by  August  Schmitz,  Dusseldorf,  Germany 

fore,  impossible  to  weld  tin  plate  with  satisfactory  results  with- 
out first  carefully  removing  the  tin  at  the  welding  line  and  its 
immediate  vicinity,  in  the  same  way  as  the  zinc  is  removed  from 
galvanized  plates. 

Manufacture  of  Tubing  by  Autogenous  Welding.  —  The  trend 
of  industrial  processes,  to-day,  is  in  the  direction  of  continuity. 
If  a  process  can  be  made  continuous,  a  great  advantage  is  gained, 
other  things  being  equal.  It  is  no  wonder,  then,  that  in  conse- 
quence of  the  enormous  demand  for  water,  gas,  and  steam  pip- 
ing, very  determined  efforts  have  been  made  to  produce  tubing 


224  TUBE   WELDING 

by  the  process  of  rolling.  The  efforts  have  been  successful,  and 
steel  tubing  is  now  made  in  large  quantities  by  this  method. 
Strips  of  flat  steel  are  rolled  longitudinally  between  successive 
pairs  of  rolls  until  the  edges  meet  or  overlap.  They  are  then 
butt-  or  lap-welded. 

In  Germany,  tubing  is  made  by  the  rolling  of  sheet  metal  and 
the  subsequent  welding  with  oxygen  and  acetylene,  the  process 
being  continuous  and  a  special  welding  machine  being  used. 
The  rolling  machine  is  of  the  type  shown  in  Fig.  2.  This  machine 
receives  the  metal  in  long  flat  strips,  which  have  either  been  spe- 
cially rolled  or  cut  to  the  required  width.  The  first  operation  is 
accomplished  by  a  pair  of  rolls  which  bend  the  longitudinal 
edges  upward.  These  bent-up  edges  will  ultimately  form  the 
"roof"  of  the  tube.  It  is  important  that  the  degree  of  curva- 
ture of  the  bends  shall  be  precisely  that  of  the  finished  tube. 
Another  pair  of  rolls  just  ahead  receives  the  strip  and  bends  it 
into  a  U-shaped  form;  the  upper  ends  of  the  U-curve,  however, 
are  bent  toward  each  other  because  of  the  side  bends  formed  by 
the  previous  pair  of  rolls.  Another  pair  of  rolls  is  now  employed 
to  receive  the  U-shaped  strip,  causing  it  to  approximate  still 
more  closely  the  tube-shape.  Finally,  another  pair  of  rolls  com- 
pletes the  bending  to  shape;  a  mandrel  is  employed  with  this 
pair.  In  case  very  elastic  material  is  employed,  it  is  advisable 
in  the  first  pass  to  bend  the  axial  portion  so  that  when  the  tube 
is  shaped  it  will  point  in  toward  the  inside  of  the  tube.  In  the 
last  operation,  this  bend  will  be  eliminated  by  the  mandrel. 
The  object  is  to  obtain  a  joint  with  no  tendency  to  open. 

When  a  strip  which  has  been  cut  from  a  sheet  in  the  ordinary 
way  is  thus  bent  together,  there  will  be  a  V-shaped  groove  along 
the  joint.  The  reason  for  this  is  that  the  external  circumference 
of  an  annular  ring  is  longer  than  the  internal  one.  The  strip 
is  of  the  same  width  on  both  sides,  so  that  when  one  side  is  bent 
to  form  a  complete  inner  circle  there  is  not  enough  material  for 
the  outer  circle.  The  weld  can  still  be  made,  but,  as  machine 
welds  use  no  additional  metal,  the  section  at  the  weld  will  be 
thinner  than  it  ought  to  be.  If  the  tubing  is  made  of  quite  thin 
metal,  no  especial  difficulty  will  arise  from  the  formation  of  a 


TUBE   WELDING  225 

groove;  but,  when  the  wall  is  rather  thick,  strips  which  have 
been  especially  rolled  to  provide  a  greater  width  on  one  side 
than  on  the  other  should  be  used.  When  such  a  strip  is  bent  to 
the  final  shape,  there  is  a  narrow  V-shaped  groove  with  ridges 
on  each  side.  A  narrow  groove  is  advisable,  because  it  admits 
the  flame  to  the  entire  depth  of  the  joint. 

The  Tube  Welding  Machine.  —  The  welding  machine  is 
rather  simple.  Two  pairs  of  compression  rolls  are  placed  a  short 
distance  apart,  as  indicated  in  the  diagrammatical  view,  Fig.  3. 
These  rolls  carry  the  tube  along,  the  one  pair  receiving  it  from 
the  tube  rolling  mill.  Between  the  two  pairs  of  rolls  a  standard 
is  placed  to  which  is  secured  the  device  which  holds  the  torch. 


Machinery 


Fig.  3.   Principle  of  Autogenous  Tube  Welding  Machine 

This  latter  has  its  tip  directed  downward  and  toward  the  un- 
welded  joint.  The  angle  of  inclination  is  about  45  degrees.  The 
tubing,  as  it  is  fed  along  by  the  first  pair  of  rolls,  cannot  always 
be  depended  upon  to  keep  its  unwelded  joint  in  a  constantly 
uniform  position.  It  is,  however,  necessary  that  the  working 
flame  of  the  torch  and  this  joint  shall  be  in  an  exact  relation  to 
each  other.  Therefore,  a  holder  is  provided  which  carries  a  roll 
or  wheel  having  a  thin  edge  or  projection  on  its  periphery.  This 
edge  enters  into  the  groove  at  the  joint  and  controls  its  position 
just  before  it  reaches  the  torch.  This  machine  is  made  of  the  du- 
plex type,  so  that  two  welding  operations  may  be  handled  at  the 
same  time;  a  torch  and  the  necessary  rolls  are  arranged  on  each 


226  TUBE  WELDING 

side  of  the  bed.  Comparatively  thin  tubing,  say,  0.04  inch 
in  thickness,  can  be  welded  at  the  rate  of  about  8  inches  per 
second,  or  about  40  feet  per  minute. 

General  Considerations  in  Tube  Welding.  —  It  is  frequently 
the  custom  in  the  bicycle  industry  to  draw  tubing  to  an  oval  or 
elliptical  section.  The  most  severe  stresses  to  which  such  ellip- 
tical tubing  is  subjected  would  tend  to  injure  the  weld,  if  the 
latter  should  be  located  at  the  end  of  either  axis  of  the  ellipse. 
It  has  been  found  advisable,  therefore,  to  locate  the  seam  to 
one  side  of  the  "sharp"  end  of  the  ellipse.  A  Swedish  charcoal 
iron,  containing  very  little  carbon,  is  claimed  to  be  most  suitable 
for  this  class  of  work. 

In  the  rolling  of  tubes  of  small  diameter,  it  is  permissible  to 
roll  in  a  longitudinal  direction,  but  with  greater  diameters,  it 
becomes  necessary,  or  at  least  advisable,  to  discard  the  contin- 
uous method  and  use  rolls  or  other  devices  the  axes  of  which  are 
parallel  with  that  of  the  tube.  Machines  specially  built  for  this 
service  bend  the  sheets  quickly  to  the  required  cylindrical  form. 
Diameters  of  from  3  to  10  inches  are  readily  handled,  the  material 
having  a  thickness  up  to  J  inch.  The  forming  process  requires  from 
7  to  12  minutes  for  each  section  of  tubing,  according  to  the  length. 
Large  tubes  are  usually  welded  autogenously  by  hand. 

Tests  on  Welded  Tubing.  —  That  large  pipe  made  by  the 
oxy-acetylene  process  is  reliable  is  indicated  by  the  following 
test:  Two  sections  of  such  pipe,  each  about  39  feet  long  and  35 
inches  inside  diameter,  had  their  flanges  bolted  together  to  form 
a  single  length  of  nearly  80  feet.  The  supports  were  placed  at 
the  ends  so  that  the  full  length  between  them  was  unsupported. 
Then  the  double  length  of  tubing  was  loaded  with  about  thirty 
men,  or,  in  other  words,  a  load  of  more  than  two  tons  was  sup- 
ported. Of  course  this  test  does  not  take  into  account  the  ques- 
tion of  the  "water- tightness"  of  the  weld.  However,  a  test  was 
carried  out  upon  another  piece  of  welded  tubing  —  this  time  a 
bend  —  of  about  2  feet  inside  diameter.  The  tube  did  not  leak 
under  a  pressure  of  about  365  pounds  per  square  inch.  Another 
piece  of  tubing  about  31  or  32  inches  in  diameter  has  been  made 
by  the  welding  process  from  material  which  was  about  0.4  inch 


TUBE   WELDING  227 

thick.  A  drainage  system  for  a  lock  of  the  Kaiser- Wilhelm 
canal  contains  about  2000  feet  of  pipe  welded  by  the  autogenous 
process.  One  German  firm  is  manufacturing  hot- water  heaters 
by  the  same  process. 

Acetylene  Welding  of  Gas  Pipe.  —  George  H.  Manlove,  in 
the  Iron  Trade  Review,  describes  a  method  of  making  welded 
joints  in  steel  and  wrought-iron  gas  mains  by  means  of  the  acet- 
ylene flame,  which  has  taken  the  place  of  threaded  joints  and 
couplings.  A  skilled  operator  will  produce  unions  the  strength 
of  which  ranges  from  80  to  95  per  cent  of  the  strength  of  the 
pipe,  and  by  building  up  sections  at  the  weld  the  strength  is 
increased  even  beyond  that  of  the  pipe.  Joints  of  this  type  per- 
mit great  flexibility  in  construction  and  are  claimed  to  .assure 
absolute  tightness.  As  far  as  possible  the  lengths  of  pipe  are 
welded  together  outside  the  trench  with  a  welding  flame  of  a 
temperature  of  approximately  1650  degrees  F.  The  metal  on 
each  side  of  the  weld  is  fused  and  pure  wrought  iron  is  fused  on 
the  pipe  to  form  a  fusion  weld.  The  limit  of  the  number  of  sec- 
tions which  can  be  welded  together  before  lowering  into  the 
trench  is  apparently  limited  only  by  city  street  traffic  conditions 
and  by  the  length  of  time  which  a  trench  can  remain  open. 
In  the  country,  it  is  not  unusual  to  weld  as  much  as  1000  feet  of 
pipe  at  one  time,  and,  in  one  case,  4000  feet  of  8-inch  pipe  were 
welded  before  placing  in  the  trench. 

After  a  section  of  pipe  is  welded,  it  is  rolled  into  the  trench 
and  welded  to  the  main  already  laid,  a  bell  hole  being  dug  to 
allow  the  operator  to  weld  entirely  around  the  joint.  The  longer 
the  sections  are  made  before  the  pipe  is  lowered  into  the  trench, 
the  fewer  bell  holes  are  necessary,  and  the  more  quickly  will  the 
work  proceed.  After  a  section  of  pipe  is  finished,  it  is  capped  at 
both  ends  and  tested  for  leaks  at  any  desired  pressure.  One  of 
the  advantages  of  this  process  is  that  lighter  pipe  may  be  used 
than  where  screw-joint  couplings  are  used,  as  it  is  not  necessary 
to  allow  any  thickness  of  the  pipe  for  threading.  This  results 
in  a  saving  in  cost,  and  in  some  parts  of  Europe  it  has  been 
demonstrated  that  pipe  of  40  per  cent  of  the  usual  thickness  may 
be  utilized  with  the  same  results. 


CHAPTER    IX 
OXY-ACETYLENE  WELDING  OF  TANKS  AND  RETORTS 

ONE  of  the  most  important  applications  of  the  oxy-acetylene 
welding  process  is  in  connection  with  the  manufacture  of  tanks 
and  cylinders  from  sheet  metal.  In  this  field,  the  new  process 
promises  to  supersede  soldering  and  riveting  to  a  very  large  ex- 
tent. The  advantage  over  soldering  consists  principally  in  the 
increased  strength  of  the  joint  and  the  equality  of  the  expan- 
sion and  contraction  of  the  metal  in  the  seam  and  in  the  work. 
There  is  also  much  less  likelihood  of  the  occurrence  of  poisonous 
corrosions. 

Form  of  Joint.  —  In  constructing  vessels  of  sheet  metal  which 
are  subjected  to  alternations  of  high  and  low  internal  pressures, 
it  is  generally  advisable  to  use  special  forms  of  joints  at  the 
corners  or  to  avoid  corner  joints  entirely.  The  stresses  on  the 
corner  joints  become  very  severe,  if  the  corners  are  of  right-angled 
shape.  If  the  corner  is  rounded,  the  effect  of  the  internal  pres- 
sure at  the  joint  is  reduced.  In  Fig.  i,  for  example,  if  the  welded 
joint  is  made  at  the  square  corner  A  B,  it  will  be  located  at  the 
point  where  the  stresses  on  it,  acting  as  indicated  by  the  arrows, 
will  be  most  severe.  By  forming  the  joint  in  the  various  ways 
shown  in  Fig.  2,  the  weld  will  be  considerably  strengthened  as 
compared  with  a  weld  that  merely  joins  the  two  sides  at  the 
corner  AB  in  Fig.  i.  It  is  still  better,  however,  to  remove  the 
joint  from  the  corner  altogether.  In  Fig.  3  are  shown  the  methods 
used  for  doing  this.  The  best  method  of  all  to  relieve  the  welds 
of  the  excessive  corner  stresses  is  to  change  the  horizontal  sec- 
tion to  that  of  a  circle. 

Tops  and  Bottoms  of  Sheet-metal  Vessels.  —  One  of  the  most 
difficult  operations  in  the  welding  of  tanks  and  retorts  is  the 
attaching  of  the  tops  and  bottoms  to  cylindrical  vessels.  One 
of  the  first  methods  employed  was  that  of  making  a  joint  as 

228 


WELDING   TANKS   AND   RETORTS 


229 


shown  in  Fig.  4.  The  welding  was  done  from  the  outside  and 
could  be  well  finished.  However,  when  the  vessel  was  subjected 
to  pressures  from  within,  a  combination  of  compressive  and  ten- 
sional  stresses  was  produced  at  the  weld,  thus  causing  cracks. 
To  overcome  this  difficulty,  joints  as  indicated  in  Fig  5.  were 
made.  Where  the  metal  is  quite  thin,  sufficient  contact  of  the 
surface  can  be  secured  by  bending  the  metal  outward  to  form  a 
kind  of  a  flange.  By  using  more  welding  material  than  is  nec- 
essary to  produce  a  joint  flush  with  the  adjoining  surfaces,  a 
stronger  weld  can  also  be  made. 


Pig.  3 


Machinery 


Figs.  1  to  4.   Illustrations  showing  Various  Methods  of  Making 
Welded  Joints 

In  all  these  cases,  the  top  or  bottom  is  assumed  to  be  convex 
on  the  exterior.  Another  method,  shown  in  Fig.  6,  is  to  make  it 
concave  on  the  outside.  Such  forms  are  especially  suitable  for 
bottoms.  In  Fig.  6,  the  run  of  the  bottom  is  bent  and  the  edges 
of  the  bottom  and  of  the  cylinder  are  both  beveled  to  provide  a 
welding  groove.  Another  method  which  does  not  necessarily 
include  concaving  is  to  bend  up  the  rim  of  the  bottom  for  a  short 
distance,  the  dimensions  of  the  piece  being  such  that  this  rim 
snugly  envelops  the  cylinder;  the  two  may  then  be  welded 
together. 

The  use  of  flat  tops  and  bottoms  should  be  avoided.  The  ex- 
pansion and  contraction  of  these  during  welding  are  different 
from  those  of  the  cylinder.  The  flat  piece  does  not  yield  to  the 


230 


WELDING   TANKS   AND   RETORTS 


cylinder,  and,  hence,  the  work  is  likely  to  be  distorted.  The 
convexing  and  concaving  of  the  tops  and  bottoms  provides  a 
suitable  margin  for  yield.  Two  forms  of  bottoms  are  shown  in 
Fig.  7,  in  both  of  which  elasticity  in  the  diameter  is  provided 
for.  The  bending  in  of  the  edges  enables  the  cylinder  wall  to 
support  the  bottom  when  the  latter  is  under  pressure  from  within. 
In  some  cases,  it  may  be  necessary  to  prevent  diametral  expan- 
sion of  the  cylinder  when  welding.  A  heavy  removable  band  of 
metal  in  the  form  of  a  hoop  may  be  used  for  this  purpose.  It 
is  placed  close  up  to  the  location  of  the  seam.  Most  of  the  heat 


-Fig- 6 


Pig.  7 


Pig.  8 


Fig.  9 


Machinery 


Figs.  5  to  9.    Methods  of  Welding  Tops  and  Bottoms  to  Cylindrical  Shells 

from  the  cylinder  will  then  be  absorbed  and  dissipated  by  this 
hoop. 

An  interesting  example  of  the  application  of  the  foregoing 
principles  is  afforded  by  a  large  containing  vessel  constructed  by 
Munk  &  Schmitz,  Cologne-Bayenthal,  Germany.  This  vessel  is 
a  cylindrical  shell,  closed  at  the  top  and  bottom,  and  is  formed 
of  sheets  0.40  inch  thick  in  the  cylindrical  portion  and  0.83  inch 
thick  in  the  end  portions.  The  vessel  is  15  feet  high  and  over  9 
feet  in  diameter.  All  joints  were  made  by  the  oxy-acetylene 
torch  and  the  vessel  successfully  withstood,  when  tested,  a  pres- 
sure of  90  pounds  per  square  inch. 

Welding  Tops  and  Bottoms  to  Cylindrical  Vessels.  —  If  the 
joining  of  the  top  to  the  cylindrical  shell  were  made  at  the  pre- 


WELDING   TANKS   AND   RETORTS 


^    STEEL 


STEEL 


cise  point  where  geometrically  the  side  of  the  wall  joins  the  top, 
as  -shown  in  Fig.  8,  an  outward  pressure  exerted  from  within  and 
tending  to  produce  a  spherical  shaped  bottom  would  tend  to 
make  the  angles  at  A  more  obtuse  and  would  thus  produce  a 
tensional  stress  on  the  inner  portion  and  a  compressive  stress 
on  the  outer  portion  of  the  weld.  Hence,  it  should  be  carefully 
noted  that  this  method  of  joining  ends  to  cylindrical  shells  is 
objectionable,  and  that  the  methods  shown  in  Fig.  $  should,  in 
general,  be  adopted. 

It  is  also  very  important 
in  forming  welds  of  the  type 
described  not  to  forget  the 
effects  of  expansion  and  con- 
traction. It  is  recommended 
that  the  weld  be  hammered 
during  the  cooling-off  pro- 
cess. The  hammering  should 
be  discontinued  while  the 
metal  is  still  quite  hot,  and 
should  not  be  continued  be- 
low the  point  where  a  horse- 
shoe magnet  attracts  the 
iron;  in  fact,  at  this  point, 
one  has  perhaps  gone  a  little 
too  far.  Subsequent  to  the 
cooling,  the  region  that  has 
been  exposed  to  the  high 
temperature  should  also  be  well  annealed.  This  may  be  done  by 
using  two  oil  torches  for  gradual  reheating,  one  from  the  inside 
and  one  from  the  outside.  Incidentally  it  might  be  mentioned 
that  in  performing  the  welding  operation  it  is  also  often  advis- 
able to  use  two  welding  torches,  in  which  case  a  weld  of  the 
double-V  character,  as  shown  in  Fig.  9,  will  be  produced.  The 
bottom  of  such  a  vessel  should  be  so  arranged  that  the  weld  is 
not  located  where  the  weight  of  the  vessel  itself  comes  upon  it. 

Example  of  Welding.  —  As  a  practical  example,   the  illus- 
trations, Figs,  n,  12,  and  13,  are  shown,  indicating  the  progres- 


-WELD 


Machinery 


Fig.  10.   Example  of  Tank  welded  by  the 
Oxy-acetylene  Process 


8    3    & 
3    j±  ° 

ft     cf    O 


1 


j  CL  - 

r*     f?    Q  P*    P 

o    CD  crq    <* 

"        ro  ^*        ^A 


rH%       M          h^          >~™ 

8*1  le 

I?s-f 

rN      %^          H^       h-^     O 


WELDING   TANKS   AND   RETORTS 


233 


Bournonville  tip  was  employed  in  making  the  straight  weld  in 
the  shell,  and  a  No.  8  tip  was  used  for  the  ends.  The  straight 
weld  was  made  in  45  minutes  at  a  cost  of  $1.62  (exclusive  of 
labor,  but  including  depreciation) ;  the  circular  weld  at  the  con- 
vex end  required  2.67  hours  and  cost  $6.99;  the  circular  weld 
at  the  concave  end  required  two  hours  and  cost  $5.24.  At  thirty 
cents  per  hour,  the  labor  cost  would  be  about  $1.63,  making  a 
total  cost  of  $15.48.  These  tanks  are  used  at  a  maximum  work- 
ing pressure  of  300  pounds  per  square  inch.  A  water-cooled 
torch  was  employed  in  part  of  this  work. 


Flj.  16 


Figr.  14 


Fiff.  16 


Machinery 


Figs.  14,  15,  and  16.     Methods  of  Welding  Spouts  to  Household  Utensils 

Welding  of  Household  Utensils.  —  Some  forms  of  household 
utensils,  such  as,  for  example,  coffee  and  tea  pots,  cause  consid- 
erable difficulties  in  their  manufacture,  particularly  in  connec- 
tion with  the  attachment  of  the  spout.  Soldering  has  been  used 
to  a  great  extent  in  making  these  joints.  However,  the  basic 
material  of  the  solder  is  altogether  different  from  the  material 
united.  The  uses  to  which  the  vessels  are  put  expose  the  joints 
to  the  action  of  acids,  and  galvanic  currents  are  set  up  which  in- 
jure the  joint.  Aluminum  vessels  are  especially  exposed  to  the 
action  of  these  currents,  because  this  metal  is  electropositive  to 
nearly  all  of  the  common  metals.  One  means  to  obviate  the  dif- 
ficulty is  to  bend  the  metal  of  the  main  vessel  or  body  inwards  at 
the  hole  for  the  spout.  The  material  of  both  the  body  and  the 
spout  is  then  bent  into  a  fold  on  the  interior,  no  soldering  mate- 


234  WELDING  TANKS  AND  RETORTS 

rial  being  used.  The  presence  of  this  fold  on  the  inside,  however, 
is  very  objectionable.  Even  though  it  is  closed  when  the  vessel 
is  new,  the  effect  of  repeated  heatings  is  liable  to  open  it,  and 
the  crevice  becomes  a  trap  for  various  small  particles,  which 
prevents  effective  cleaning.  The  oxy-acetylene  welding  pre- 
sents the  best  solution  of  the  foregoing  difficulties. 

Joints   for    Household    Utensils.  —  When    seeking   to  unite 
the  spout  and  the  body  by  the  oxy-acetylene  torch,  the  worker 


Fig.  17.  Example  of  Welding  Copper.  Kettle  is  5  Feet  6  Inches  in 
Diameter,  31  Inches  Deep,  and  Used  under  Pressure.  All  Seams 
are  Welded  on  Both  Sides 

is,  however,  confronted  with  several  difficulties,  especially  if  the 
sheet  metal  is  aluminum.  The  expansion  and  contraction  of 
aluminum,  due  to  temperature  changes,  as  already  mentioned, 
is  very  rapid,  so  that  the  operator  must  guard  against  distor- 
tions of  the  work.  The  melting  point  of  the  metal  is  low,  so 
that  holes  are  apt  to  be  made  in  thin  metal.  Heated  aluminum 
is  very  readily  oxidized,  with  the  result  that  a  proper  inter- 
mingling of  the  material  is  difficult.  In  view  of  these  facts,  it 
is  recommended  that  the  joint  be  placed  away  from  the  main 
body,  that  welding-wire  be  dispensed  with,  and  that  a  suitable 


WELDING   TANKS   AND   RETORTS 


235 


flux  be  employed.  In  Fig.  14  is  shown  a  joint  which  eliminates 
the  necessity  for  the  welding- wire ;  the  spout  fits  closely  into 
the  hole  and  is  introduced  far  enough  to  protrude  about  |  inch 
into  the  interior,  the  projection  thus  furnishing  the  welding  ma- 
terial. There  is  considerable  advantage,  of  course,  in  thus  elimi- 
nating the  handling  of  the  wire  as  far  as  the  worker  is  concerned, 
and  another  advantage  is  that  the  welding  material  is  precisely 
the  same  as  the  material  of  the  work.  It  is  difficult,  however, 
to  operate  on  the  interior,  but  this  difficulty  may  be  reduced 


WELD 


p 

Q 

CONtTRuCMON 

Machinery 


Fig.  18.    Recommended  Forms  of  Joints 

by  using  a  tip  of  special  form.    The  appearance  of  the  exterior, 
however,  is  good. 

Another  form  of  joint  is  shown  in  Fig.  15.  Here  the  diameter 
of  the  hole  is  first  made  smaller  than  the  interior  diameter  of 
the  lower  end  of  the  spout.  The  material  is  then  bent  outwards 
to  form  a  ridge  of  the  same  diameter  as  that  of  the  spout  end. 
The  body  and  spout  can  then  be  butt-welded  by  using  weld- 
ing-wire. It  is  preferable,  however,  to  bend  the  edge  of  the 
projection  from  the  vessel  outward,  thus  supplying  the  needed 
welding  metal,  or  the  auxiliary  metal  may  be  provided  by 
bending  the  edge  of  the  spout  outwards,  a  joint  of  this  kind 
being  shown  in  Fig.  16.  In  either  case,  the  ring  of  metal  pro- 
truding at  the  joint  will  not  be  thicker  than  J  inch  in  a  radial 
direction.  In  both  cases,  the  interior  is  smooth. 


236 


WELDING  TANKS  AND   RETORTS 


Design  of  Work  for  Welding.  —  The  design  of  work  for  weld- 
ing is  an  important  matter,  and  one  which  must  receive  careful 
attention  in  each  individual  case.  The  first  point  to  be  consid- 
ered is  that  of  the  internal  stresses  set  up  by  contraction  in  a 
welded  piece  as  it  cools.  These  stresses  are  inevitable,  but  may 
be  greatly  reduced  by  care  in  arranging  the  form  and  setting  of 
the  work.  For  instance,  a  boss  or  ferrule  should  not  be  welded 
onto  a  flat  plate;  the  latter  should  be  dished,  and  will  then,  if 
of  good  soft  metal,  adapt  itself  to  the  contraction  stresses.  In 


41%- =» 

WELDx  '%' 


Machinery 


Fig.  19.  Welded  Expansion  Pipes 

building  up  tanks  from  flat  sheets,  it  is  impossible  to  avoid  some 
buckling  of  the  plates  by  thermal  stresses,  but  the  deformation 
can  be  kept  to  a  minimum  by  a  skillful  operator. 

In  making  a  butt  strap  joint,  as  shown  at  A  in  Fig.  18,  the 
butting  plates  should  not  be  set  in  contact  to  begin  with,  other- 
wise contraction  stresses  will  force  them  together  and  tend  to 
shear  the  strap  welds;  there  are  no  stresses  of  this  nature  if 
the  plates  P  and  Q  are  set  slightly  apart  before  welding  on  the 
strap.  It  is  impossible  to  secure  a  weld  of  any  considerable 


WELDING  TANKS  AND  RETORTS 


237 


depth  between  two  flat  surfaces  in  contact,  and  it  is  useless  to 
adopt  any  design  which  depends  upon  this  being  done.  Either 
the  pieces  must  be  set  slightly  apart  or  chamfered  (or  both), 
as  shown  at  B,  so  that  filling  metal  can  be  introduced  and  the 
weld  built  upwards  from  the  bottom,  or  one  piece  must  be 
shortened  so  that  it  makes  quite  a  short  flat  contact  with  the 
second  piece,  metal  being  then  built  on  to  replace  the  missing 
part  of  the  first  piece  and  unite  firmly  with  the  second  as  it  is 
worked  into  position  (see  black  areas,  at  C). 

The  best  design  for  welding  an  end  into  a  cylindrical  vessel 
to  resist  internal  pressure  is,  as  already  mentioned,  a  matter  of 


COMPLETE 
CIRCUMFERENTIAL 
'WELD 


Fig.  22 


Machinery 


Figs.  20,  21,  and  22.   Circumferential  Welds  on  Large  Cylinders 

great  importance;  the  Steel  Barrel  Co.,  Ltd.,  recommends  the 
joint  shown  at  D.  The  domed  end  is  the  form  best  resisting  in- 
ternal pressure,  and,  by  fitting  the  flange  of  the  end  inside  the 
cylinder,  a  good  fit  is  easily  obtained. 

Welded  Expansion  Pipe.  —  Acetylene  welded  expansion  pipes 
of  the  types  shown  in  Fig.  19  have  been  built  successfully  in 
sizes  up  to  4  feet  6  inches  internal  diameter,  to  go  between  steam- 
turbines  and  their  condensers  or  in  the  connection  of  gas-engine 
exhaust,  steam  separators,  etc.  About  i  in  10  or  15  lateral  ex- 
pansion or  contraction  is  easily  provided  in  an  expansion  pipe 
of  this  construction,  2  inches  expansion,  for  instance,  being  taken 
up  easily  and  safely  by  20  inches  or  30  inches  of  welded  "con- 
certina" pipe.  The  pipe  shown  to  the  left,  in  Fig.  19,  is  built 


238  WELDING  TANKS  AND  RETORTS 

up  from  circular  sections  f  inch  thick  welded  together  along 
their  inner  and  outer  peripheries  and  welded  onto  a  J-inch 
flange  at  each  end,  by  building  on  metal  as  shown  by  the  black- 
ened areas.  In  the  alternative  construction  to  the  right  butt 
welds  are  made  in  the  semicircular  bends  between  sections. 
The  butt  welds  can  be  made  at  the  rate  of  8  or  10  feet  per  hour, 
and  the  built-up  welds  at  the  rate  of  5  or  6  feet  per  hour. 

Mixed  Welding  on  Large  Tank  Construction.  —  In  boiler 
and  still  construction  and  in  building  up  cylindrical  tanks  for 
oil  storage  or  transport  or  for  use  as  air  receivers,  etc.  —  where 
over-all  dimensions  are  calculated  by  feet  and  plates  J  inch  or 
so  in  thickness  are  employed  —  it  is  usually  convenient  to  make 
some  joints  by  electric  arc  welding  and  others  by  the  acetylene 
process.  As  regards  the  plate  seams,  the  thickness  of  metal 
operated  on  is  the  same  for  both  processes  in  any  particular 
tank,  but  the  longitudinal  butt  joints  are  most  quickly  and 
conveniently  made  by  arc  welding,  while  circumferential  lap  or 
strap  joints,  flange  attachments,  and  end  joints  are  best  treated 
by  acetylene  welding.  A  longitudinal  joint  in  a  large  cylindri- 
cal tank  of  J-inch  plate  can  be  made  at  about  from  8  to  10  feet 
per  hour  by  the  electric  arc  process,  while  the  main  circumfer- 
ential lap  or  strap  joints  can  be  made  by  the  acetylene  process 
at  from  6  to  8  feet  per  hour. 

In  making  a  complete  circumferential  lap  weld,  it  should  be 
noted  that  the  outside  seam  A,  Fig.  20,  should  be  welded  all 
around  the  cylinder  and  the  inside  seam  B  simply  tacked  by 
short  acetylene  welds  at  intervals.  These  tacking  welds  hold 
the  plate  in  position,  but  do  not  imprison  air  'between  the  lap- 
ping plates;  any  attempt  to  make  both  welds  A  and  B  com- 
plete will  cause  trouble.  For  a  similar  reason,  in  the  inside 
and  outside  butt  strap  joints  shown,  Figs.  21  and  22,  complete 
circumferential  welds  must  only  be  made  at  A ,  the  seam  B  being 
left  open  or  merely  tacked  down  at  intervals. 


CHAPTER  X 
GENERAL  CONSIDERATIONS  IN  OXY-ACETYLENE  WELDING 

IT  should  be  understood  that  what  follows  is  written,  not 
for  the  purpose  of  discouraging  anyone  who  is  considering 
the  use  of  the  oxy-acetylene  apparatus,  but  in  order  to  coun- 
teract the  ideas  which  frequently  exist,  and  which  unfortu- 
nately are  frequently  cultivated  by  salesmen  and  advertising 
matter,  that  it  is  an  exceedingly  simple  matter  for  anyone  to 
learn  to  do  good  work  by  oxy-acetylene  welding  in  a  short  time, 
and  that,  by  following  printed  instructions,  anyone  can  become 
expert.  These  fallacies  are  responsible  for  many  disappoint- 
ments, and  the  apparatus  and  method  have  been  denounced 
many  times,  when  the  whole  trouble  lies  in  the  lack  of  experi- 
ence and  knowledge,  even  where  the  apparatus  is  first-class  and 
adapted  to  the  purpose. 

In  his  thirty  years'  experience  with  mechanical  matters  of 
many  kinds,  the  author  has  not  seen  any  process  so  apparently 
easy  as  the  handling  of  any  oxy-acetylene  welding  torch  by  an 
expert  welder.  He  soon  discovered,  however,  when  he  took  a 
torch  in  his  hand,  that  what  appeared  so  easy  was  in  reality  a 
complicated  matter,  comprising,  among  other  things,  melting  the 
metal,  securing  a  good  weld,  adding  metal  and  flux,  keeping  the 
melted  metal  from  running  away  where  it  was  not  wanted, 
preventing  hard  spots,  getting  sufficient  —  but  not  too  much  — 
metal  in  the  weld,  avoiding  pin  holes  and  strains  in  the  weld, 
keeping  the  parts  in  line,  and  handling  the  heated  pieces.  Be- 
sides all  this,  no  two  metals  are  amenable  to  the  same  treat- 
ment, and  different  pieces  of  the  same  metal  often  require  vastly 
different  methods  to  handle  them  successfully. 

Unusual  Difficulties  in  Welding.  —  Two  examples  may  be  men- 
tioned to  illustrate  some  of  the  difficulties  met  with  in  welding. 
The  first  is  a  three-throw  crankshaft,  with  bearings  ab^ut  3^ 

239 


240  GENERAL   CONSIDERATIONS 

inches  in  diameter  which  had  the  coupling  flange,  about  8 
inches  in  diameter  and  i|  inch  thick,  broken  off  square  at  the 
end  of  the  end  bearing.  The  material  was  cast  steel,  and  the 
shaft  was  very  old,  probably  twenty-five  years.  The  flange  was 
bored  out  to  within  -^  inch  of  the  size  of  the  bearing,  leaving 
just  enough  to  set  it  by,  some  of  the  metal  was  melted  down  to 
tack  it,  and  an  attempt  was  made  to  proceed  by  using  regular 
steel  welding-wire,  but  this  could  not  be  done.  Several  differ- 
ent makes  of  cast  steel  were  tried  without  success.  It  was  fi- 
nally necessary  to  melt  down  enough  of  the  flange  to  extend 
entirely  across  the  end  of  the  bearing,  about  TV  inch  deep,  and 
fill  the  rest  with  cast  iron.  There  was  no  time  to  experiment, 
as  an  important  ferry  was  tied  up.  At  the  time,  some  doubt 
was  entertained  as  to  the  strength  of  the  weld;  but  as  it  has  lasted 
for  three  years,  and  as  the  break  was  probably  caused  by  the 
timbers  holding  up  the  driving  shaft  (which  was  coupled  to  the 
crankshaft)  giving  way  due  to  decay,  there  will  probably  be 
no  more  trouble. 

The  other  case  was  a  casting,  apparently  of  brass,  and  weigh- 
ing not  more  than  three  pounds.  As  is  customary  at  the  plant 
where  the  work  was  done,  rolled  Tobin  bronze  rods  were  used  to 
weld  it,  but  without  success.  It  was  found  that  the  melting 
points  of  the  casting  and  Tobin  bronze  were  so  different  that  a 
tip  heavy  enough  to  melt  the  casting  would  blow  the  Tobin 
bronze  away  before  it  could  amalgamate  with  the  casting. 
Fortunately,  there  were  on  hand  some  manganese-bronze  sticks 
with  a  very  high  percentage  of  copper,  which  had  been  used 
experimentally,  but  were  not  suitable  for  ordinary  work,  and 
these  proved  satisfactory.  Evidently  the  casting  was  a  bronze 
with  a  high  percentage  of  copper. 

Qualifications  of  a  Welder.  —  Some  men  become  more  pro- 
ficient in  the  art  in  a  shorter  time  than  do  others;  but  even  with 
every  facility  at  hand  —  the  welding  torch  is  not  all  that  is 
needed  —  much  experience  is  required  to  become  an  all-around 
welder.  The  average  good  machinist  would  require  at  least  one 
year  in  a  repair  welding  shop,  before  he  would  be  competent 
to  take  care  of  all  kinds  of  metal  and  the  various  jobs  that  come 


GENERAL   CONSIDERATIONS  241 

in.  One  of  the  principal  qualifications  is  ingenuity.  The  welder 
must  never  admit  to  himself  the  impossibility  of  any  job. 
Whether  it  will  pay  to  do  it  is  another  question,  although  it  is 
frequently  the  determining  one.  A  heavy  weld  in  a  cheap  cast- 
ing is  possible  but  uneconomical,  and  it,  therefore,  should  not 
be  done  unless  loss  of  time  in  obtaining  a  new  piece,  or  some 
other  consideration,  outweighs  the  purely  financial  one.  Care- 
ful thought  and  planning  may  make  a  job  financially  possible, 
where  the  ordinary  methods  would  result  in  the  work  not  being 
done  at  all  or  being  done  at  a  loss.  Ingenuity  is  required  for 
such  thinking  and  planning;  and  from  it  follow  new  methods, 
easier  and  cheaper,  which  result  in  an  increase  in  knowledge 
and  ability  and  in  the  advancement  of  the  art. 

Trade  Knowledge  Required.  —  It  is  not  necessary  for  a  man 
to  follow  any  special  trade  in  order  to  become  a  good  welder; 
in  fact,  some  knowledge  of  many  trades  is  necessary,  and  the 
more  known  about  them  the  better  the  welder  is  equipped.  He 
should  be  somewhat  of  a  machinist,  blacksmith,  boilermaker, 
patternmaker,  molder,  stationary  engineer,  electrician,  and 
draftsman.  He  should  have  considerable  knowledge  of  the  con- 
struction and  operation  of  automobiles,  gas  engines,  and  farm 
machinery.  An  acquaintance  with  contractors'  machinery  and 
methods  of  all  kinds  is  valuable;  and  any  mechanical  experi- 
ence that  may  have  fallen  to  his  lot  is  certain  to  be  used  sooner 
or  later.  A  knowledge  of  the  principles  of  the  strength  of  ma- 
terials is  very  useful  in  deciding  how  to  reinforce  a  weak  part 
in  the  best  manner.  For  instance,  it  is  common  for  a  customer 
to  request  that  his  automobile  frame  be  strengthened  by  weld- 
ing a  flat  piece  to  the  web  of  the  channel  inside,  when  equal 
strength  with  less  weight  and  expense  may  be  obtained  by 
welding  a  piece  to  the  inside  or  outside  —  preferably  the 
latter  —  of  the  bottom  flange,  if  that  is  where  the  tensile  strain 
comes. 

Experience  proves  that,  in  many  cases,  if  a  welded  piece 
breaks,  customers  blame  the  welder,  when  full  information  shows 
that  the  fault  is  in  incorrect  construction  or  assembling.  In 
many  cases,  it  is  probable  that  if  the  original  stresses  are  put 


242  GENERAL  CONSIDERATIONS 

on  the  parts  repaired  by  welding,  breakage  will  again  occur  and 
the  work  will  be  criticised  adversely.  One  trouble  that  frequently 
arises,  or  rather  a  condition  which  causes  trouble,  is  the  inability 
or  failure  of  the  welder  to  discover  the  cause  of  breakage.  At 
first  sight,  it  would  appear  that  this  does  not  concern  him,  but 
when  further  consideration  is  given  to  the  matter  it  will  be  seen 
that  it  is  exceedingly  important  to  know  why  a  piece  breaks. 
For  example,  the  author  frequently  runs  across  cases  where  the 
piece  is  too  light,  and,  if  this  is  the  cause,  it  is  not  fair  to  the 
customer  to  continue  to  weld  the  piece,  unless  he  is  made  aware 
of  the  situation  and  advised  that  it  will  be  cheaper  and  more 
satisfactory  to  have  the  piece  made  heavier,  or  made  of  steel 
instead  of  cast  iron,  for  instance.  Not  only  is  it  unfair  to  the 
customer  to  continue  to  weld  a  piece  that  is  too  light,  but  it 
tends  to  bring  the  process  into  disrepute,  because  the  statement 
is  sometimes  made  (although  in  the  case  of  proper  welding  with- 
out any  basis)  that  while  the  metal  at  the  weld  is  strong  enough, 
the  original  piece  is  damaged  just  outside  of  the  weld.  The 
reason  for  this  kind  of  breakage  is  generally  that  the  piece  is 
too  weak,  although  in  the  case  of  some  metals,  such  as  malleable 
iron,  it  is  very  easy  to  damage  the  metal  outside  the  weld,  as 
will  be  explained  later.  Aside  from  the  above  points,  proper 
advice  to  a  customer  creates  a  feeling  of  friendship  and  good 
will  that  is  an  important  business  asset. 

An  experience  bearing  upon  the  application  of  welding,  and 
incidentally  illustrating  the  strength  of  welds,  may  be  men- 
tioned. A  piece  of  cast  iron  had  been  welded  several  times, 
never  breaking  in  the  same  place.  When  it  was  returned  the 
next  time,  inquiry  was  made  as  to  the  advisability  of  rewelding 
it,  and  it  was  stated  that  the  piece  was  so  located  in  the  ma- 
chine to  which  it  belonged  as  to  be  the  weakest  part,  so  that,  if 
any  excessive  strains  were  to  occur,  this  piece  would  break.  The 
total  number  of  welds  eventually  made  in  it  was  fourteen  and 
the  superintendent  of  the  factory  operating  the  machine  later 
stated  that  the  piece  had  been  thrown  away,  as  he  was  afraid 
that  it  was  too  strong  to  answer  the  purpose,  inasmuch  as  there 
was  very  little  left  of  it  but  welds. 


GENERAL   CONSIDERATIONS  243 

Training  of  Welders.  —  One  serious  obstacle  to  the  rapid 
development  of  oxy-acetylene  welding  in  all  branches  is  the  dif- 
ficulty of  obtaining  welders,  and  this  is  frequently  and  success- 
fully urged  against  the  purchase  of  apparatus.  The  Germans 
have  overcome  this  difficulty  by  establishing  welding  schools, 
where  not  only  workmen,  but  foremen,  superintendents,  and 
managers  receive  both  theoretical  and  practical  instruction.  It 
is  not  believed  that  such  work  should  be  done  by  the  govern- 
ment here,  but  the  manufacturers  of  welding  apparatus  should, 
in  their  own  interest,  take  such  steps  as  would  enable  schools 
to  be  maintained.  This  is  a  subject  which  cannot  be  discussed 
here,  except  to  say  that  Germany  is  far  in  advance  of  the  United 
States  in  the  development  of  oxy-acetylene  welding,  largely 
because  of  such  instruction,  and  it  is  believed  that  a  perfectly 
feasible  plan  can  be  readily  developed  to  overcome  the  present 
deplorable  lack  of  educational  facilities  here.  Whatever  sys- 
tem of  education  or  training  be  adopted,  it  is  essential  that  the 
welder  be  impressed  with  the  importance  and  necessity  of  being 
absolutely  honest,  not  only  with  his  employer  but  with  himself. 
There  is  no  credit  to  anyone  in  having  a  piece  returned  with 
a  defective  weld,  and  a  properly  trained  foreman  can  instantly 
determine  if  carelessness  caused  the  defect.  Two  or  three  in- 
stances of  such  work  should  condemn  a  welder  almost  beyond 
redemption.  Aside  from  this,  it  would  be  a  serious  matter  to 
the  average  man  to  feel  that  any  defective  work  he  had  knowingly 
done  had  resulted  in  injury  to  any  of  his  fellowmen.  Such  acci- 
dents have  occurred,  and  show  clearly  the  need  of  proper  edu- 
cation and  the  most  rigid  code  of  honor  on  the  part  of  the  welder. 

Welders  on  Repair  Work.  —  To  obtain  competent  welders  is 
not  so  difficult  in  a  shop  where  the  work  is  largely  of  one  kind 
-  thin  sheet  metal,  for  instance.  In  this  case,  the  men  become 
remarkably  expert  in  a  comparatively  short  time,  and  far  more 
so  than  a  good  all-around  man  would  be  on  their  special  work; 
but  such  a  specialist  is  of  practically  no  value  in  a  repair  shop, 
where  he  would  have  to  handle  not  only  all  sizes  of  pieces,  but 
all  kinds  of  metals.  The  author  has  found  that  the  only  possible 
way  is  to  employ  a  man  who  knows  something  about  the  prin- 


244  GENERAL  CONSIDERATIONS 

ciples  of  the  art,  and  to  teach  him,  not  so  much  how  to  weld 
but  how  to  do  the  work  so  that  as  little  machining  or  other  fin- 
ishing as  possible  has  to  be  done  after  welding,  and  so  that  the 
piece  can  be  used  after  being  welded. 

The  average  welder  pays  little  attention  to  anything  except 
welding,  and  if  he  secures  a  sound  weld,  he  feels  somewhat  ag- 
grieved if  his  attention  is  called  to  the  fact  that  the  part  is  out 
of  line  or  full  of  hard  spots,  or  has  some  other  defect  so  that  it 
is  difficult  if  not  impossible  to  use  it.  It  is  possible,  however,  to 
avoid  machining  in  many  cases  by  care  on  the  part  of  the  welder. 
For  instance,  a  frequent  accident  to  an  automobile  crankcase  is 
a  break  through  the  side.  No  machining  should  be  needed  in 
such  a  case,  and  the  faces  and  bearings  should  be  just  as  true 
after  the  welding  as  before.  It  is  admitted  without  argument 
that  this  is  not  commonly  done,  but  it  should  be.  Again,  a 
stamping  press  frame,  broken  through  one  of  the  uprights,  even 
if  the  section  is  as  large  as  4  by  1 6  inches,  should  never  have 
the  crankshaft  bearings  out  of  line  with  the  platen  more  than 
o.oio  inch,  and  good  welders  repeatedly  weld  such  pieces  with 
less  than  half  this  error. 

It  is  also  strongly  recommended  that  the  superintendent,  in  a 
shop  doing  welding,  himself  learn  to  weld;  not  with  the  idea  of 
doing  the  work,  but  so  that  he  may  be  able  to  check  the  men  as 
to  the  quality  of  their  work  and  to  decide  how  the  work  should 
best  be  done.  It  is  easy  to  deceive  a  person  who  cannot  weld, 
even  when  he  is  watching  the  work. 

Wages  of  Welders.  —  A  good  welder  is  worth  good  wages.  A 
proper  consideration  of  the  conditions  will  show  that  a  careful 
man  can  save  far  more  in  the  cost  of  gases  than  any  wages  which 
he  is  paid.  Oxygen  costs  on  the  average,  say,  i\  cents  per  cubic 
foot,  and  a  medium-size  tip  uses  from  25  to  30  feet  per  hour,  so 
that  the  oxygen  expense  runs  from  60  to  75  cents  per  hour.  The 
cost  of  acetylene  will  run,  depending  upon  how  it  is  made,  from 
20  to  50  cents  per  hour;  the  total  is  from  $i  to  possibly  $1.25  per 
hour.  It  can  be  readily  seen,  therefore,  that  carelessness  or  slow 
speed  on  the  part  of  the  welder  is  very  expensive,  and  that  it 
is  advisable  to  secure  good  men  and  pay  them  good  wages. 


GENERAL  CONSIDERATIONS  245 

In  repair  work,  no  consideration  should  be  given  to  piece- 
work or  bonus  systems  of  paying  the  men.  The  author  has  had 
a  great  deal  of  experience  with  piece-work,  and,  under  certain 
conditions,  if  properly  handled,  it  is  an  admirable  method  of 
increasing"  earnings  by  stimulating  men  to  eliminate  lost  time 
and  useless  work;  but  in  repair  work  it  is  impossible  to  set  any 
piece-work  price  that  will  be  fair  to  both  the  workmen  and  the 
employer,  and,  for  this  reason,  no  attempt  should  be  made  to 
use  it.  A  good  welder  of  the  proper  temperament,  who  is  paid 
good  wages,  will  do  good  work,  and  this  is  the  most  important 
thing  in  welding,  being  far  more  essential  than  mere  speed. 
Again,  repair  work  is  an  art;  and  a  self-respecting  welder  will 
not  permit  himself  to  be  hurried  beyond  the  rate  which  he  con- 
siders essential  to  good  work.  At  the  same  time,  he  will  not  per- 
mit himself  to  loaf;  and  a  man  who  is  so  constituted  that  he 
will  allow  himself  to  do  poor  or  slow  work  deliberately  has  no 
place  in  a  repair  shop. 

Rest  Periods  Required  on  Large  Work.  —  One  of  the  objec- 
tions raised  by  the  workmen  is  the  tremendous  amount  of  heat 
given  off  by  large  pieces  in  a  hot  fire.  A  man  cannot  do  good 
work  unless  properly  protected,  and,  in  some  cases,  it  is  impos- 
sible even  with  the  best  protection  that  can  be  afforded  for  a 
man  to  stand  the  heat  for  more  than  from  15  to  20  minutes. 
In  such  cases,  enough  extra  welders  should  be  provided  so  that 
a  man  will  work  one  period  and  rest  twice  as  long.  This  is 
particularly  necessary  on  large  welds  that  require  from  8  to  10 
hours  to  complete.  A  number  of  cases  are  on  record  where  the 
actual  welding  extended  over  more  than  24  hours.  It  has  been 
found  that  20  minutes  of  work  and  40  minutes  of  rest  for  a  man 
accustomed  to  such  work  is  satisfactory;  in  one  case,  on  account 
of  the  great  heat,  15  minutes  of  work  and  45  minutes  of  rest 
was  found  necessary.  It  is  not  advisable  in  moderately  heavy 
welding  to  have  a  man  stay  at  the  work  for  more  than  2  hours 
at  a  time. 

Cooling  the  Torch  Tips.  —  In  heavy  welding,  the  torch  tips, 
if  made  of  brass,  are  likely  to  become  overheated,  unless  great 
care  is  taken,  to  such  a  point  that  the  oxygen  pressure  will 


246  GENERAL  CONSIDERATIONS 

blow  off  the  end  of  the  tip.  This,  as  already  mentioned,  can  be 
overcome  largely  by  keeping  a  pail  of  water  nearby,  in  which 
the  end  of  the  tip  can  be  dipped  when  necessary.  It  is  objec- 
tionable to  dip  the  whole  head  of  the  torch,  as  this  is  likely  to 
distort  the  end  of  the  tip  at  the  seat  and  cause  a  leak.  The 
proper  way  is  to  dip  the  end  of  the  tip  into  the  water  and  cool 
it  slowly.  After  the  entire  tip  is  cooled,  the  head  may  then  be 
cooled,  but  not  rapidly.  This  difficulty  exists  generally  at  the 
beginning  of  a  deep  weld  where  the  whole  head  of  the  torch  is 
surrounded  by  the  hot  metal.  It  has  been  found  of  great  assist- 
ance to  weld  a  piece  of  copper  with  the  proper  size  hole  in  it 
onto  the  end  of  a  brass  tip,  being  certain  that  it  is  aligned  care- 
fully with  the  rest  of  the  tip.  This  can  be  done  by  using  a  piece 
of  the  proper  size  drill  rod.  It  will  be  found  that  this  can  be 
pulled  out  easily  as  soon  as  the  weld  is  finished,  if  care  is  taken 
not  to  weld  the  drill  rod  to  the  tip. 

Care  of  Apparatus.  —  The  torches  and  apparatus  should  be 
taken  good  care  of.  If  there  are  leaks  in  the  connections,  or 
other  defects,  they  should  be  repaired  at  once.  If  the  tips  are 
defective  and  cannot  be  repaired,  new  tips  should  be  provided. 
Good  results  cannot  be  obtained  with  defective  apparatus. 
The  quality  of  the  apparatus  purchased  should  be  high.  The 
market  is  flooded  with  cheap  apparatus,  such  as  torches,  gages, 
etc.  Imperfect  apparatus  will  produce  a  welding  flame,  but 
will  not  give  good  results  or  be  economical  in  the  use  of  gases; 
also,  they  are  frequently  infringements  of  patents  owned  by 
manufacturers  of  the  better  apparatus,  and,  therefore,  the  user 
is  liable  for  damages  as  well  as  the  manufacturer.  Only  first- 
class  apparatus  manufactured  by  responsible  firms  should  be 
used  for  welding. 

Overhead  Cost.  —  The  average  small  shop  of  any  kind  is  not 
usually  run  with  the  proper  attention  to  the  real  cost  of  the 
work.  This  is  particularly  true  in  connection  with  welding, 
because  it  is  not  generally  understood  that  there  are  other 
costs  besides  those  of  the  gases  and  labor.  Such  expenses  as 
interest,  depreciation,  insurance,  repairs,  taxes,  advertising, 
soliciting,  etc.,  have  to  be  paid  out  of  the  earnings  of  the  shop, 


GENERAL  CONSIDERATIONS  247 

although  they  are  generally  not  taken  into  account  in  the 
proper  way.  A  large  concern  with  competent  accountants 
does  take  care  of  these  things,  and  realizes  that  its  customers 
have  to  pay  for  them  in  the  price  of  the  work.  Many  small 
welding  shops  have  lost  out  by  not  paying  attention  to  these 
matters.  Again,  the  cost  of  gases  is  frequently  taken  at  the 
invoice  price  without  considering  freight  and  cartage  which 
have  to  be  paid  both  ways. 

There  are  a  number  of  other  items  that  must  be  taken  into 
account  in  order  that  the  proper  cost  of  the  work  may  be  ob- 
tained. Assume  that  a  plant  cost  $1000,  and  that  the  fixed 
charges  will  be  as  follows:  Interest,  6  per  cent;  depreciation, 
10  per  cent;  repairs,  5  per  cent;  insurance,  2  per  cent;  taxes,  i 
per  cent —  a  total  of  24  per  cent  or  $240  per  year.  The  operating 
expenses  might  be  about  as  follows:  Rent,  $35;  heat,  $5;  light, 
$2 ;  power,  $5  —  a  total  of  $47  per  month,  or  $564  per  year. 
There  will  be  miscellaneous  charges,  depending  upon  the  work 
done,  for  welding-rods,  hand  tools,  such  as  files,  chisels,  hack- 
saw blades,  etc.,  charcoal,  cartage,  and  some  other  things,  which 
will  run  up  to,  say,  $25  per  month  or  $300  per  year.  If  the  welder 
is  an  all-around  man,  his  labor  will  be  worth  at  least  40  cents 
an  hour.  A  competent  solicitor  will  cost  at  least  $75  per  month 
or  $900  per  year.  The  total  of  these  charges,  exclusive  of  the 
welder's  labor,  amounts  to  $2000  per  year.  If  oxygen  is  bought 
in  5oo-cubic-foot  lots  and  costs  two  cents  a  cubic  foot,  the  freight 
and  cartage  on  it  will  probably  cost  $3  and  $i,  respectively,  in- 
bound. Outbound,  the  tanks  weigh  somewhat  less,  and 'it  will 
be  assumed  that  the  freight  and  cartage  amount  to  $3.50.  This 
is  a  total  of  $17.50  or  3^  cents  per  cubic  foot.  If  two  3oo-foot 
tanks  of  acetylene  are  procured  at  once,  costing  two  cents  a 
foot,  the  freight  and  cartage  will  be  about  the  same  as  in  the  case 
of  oxygen,  or  a  total  of  $19.50  or  3.25  cents  per  cubic  foot.  If 
the  average  size  tip  uses  25  feet  of  acetylene  and  30  feet  of  oxy- 
gen per  hour,  the  cost  of  operating  the  torch,  aside  from  labor, 
will  be  $1.86  per  hour. 

To  summarize:  the  cost  per  hour  based  on  3000  working  hours 
per  year  will  be  as  follows:  Overhead,  $0.666;  labor,  $0.40;  gases, 


248  GENERAL  CONSIDERATIONS 

$1.86;  a  total  of  $2.926.  This  would  be  true  if  the  assumptions 
are  correct  and  if  the  welding  were  going  on  ten  hours  a  day.  If 
a  welder  were  only  occupied  in  welding  five  hours  per  day,  the 
cost  of  gases  for  the  daily  ten  hours  would  be  93  cents  per  hour, 
making  the  total  cost  about  $2  per  hour.  It  is  evident  that  care 
must  be  taken  to  insure  proper  charges  being  made  for  the  work, 
although  it  is  to  be  understood  that  the  figures  given  are  not 
actual,  and  that  they  will  have  to  be  modified  to  suit  expenses 
which  will  vary  with  different  locations.  A  common  charge  for 
machine  shop  work  is  from  60  to  75  cents  per  hour,  and  this  is 
supposed  to  cover  not  only  all  expenses,  but  profit  as  well.  The 
difference  between  these  charges  and  those  necessary  to  cover 
the  cost  and  profit  of  oxy-acetylene  welding  are  so  startling  that 
one  is  likely  to  feel  that  the  process  is  very  expensive.  It  should 
not  be  forgotten,  however,  that  the  cost  per  hour  is  not  the  correct 
basis  on  which  to  make  the  comparison.  The  results  obtained 
should  also  be  considered. 

Commercial  Limitations  of  Welding  Process.  —  The  above 
figures  also  indicate  why  in  many  cases  it  does  not  pay  to  weld 
inexpensive  parts,  and  show  the  great  necessity  of  employing 
competent  welders,  because  it  is  evident  that  a  small  amount  of 
time  lost  in  doing  a  job  may  result  in  its  costing  more  than  can 
be  charged  for  it;  so  that  quick  and  accurate  work  must  be 
done,  and  as  little  machining  or  finishing  be  required  as  possible, 
in  the  case  of  small  or  inexpensive  pieces.  There  are  many  pieces 
that  repair  shops  cannot  weld  profitably.  For  example,  the  slid- 
ing jaw  of  a  vise  frequently  breaks  off  in  front  of  the  head,  and 
while  it  is  a  perfectly  possible  job,  and  while  the  author  knows  of 
no  case  where  one  has  broken  after  welding,  it  being  possible  to 
reinforce  it  considerably,  the  cost  of  welding  compared  with  the 
cost  of  a  new  part  is  excessive.  Again,  if  the  vise  is  considerably 
worn,  as  is  generally  the  case,  it  is  a  better  investment  to  buy  a 
new  vise,  as  there  is  no  lost  motion,  and  the  condition  of  the 
jaws  is  good.  In  such  cases,  experience  and  a  thorough  knowl- 
edge of  the  real  cost  of  welding,  including  overhead  expenses,  is 
necessary  in  order  to  determine  whether  or  not  it  is  advisable 
to  weld  the  broken  part.  In  a  number  of  such  cases,  policy  may 


GENERAL   CONSIDERATIONS  249 

require  the  work  to  be  done,  even  at  a  loss,  for  the  sake  of  secur- 
ing larger  work  in  the  case  of  a  good  customer.  Such  questions 
have  to  be  decided  on  their  merits. 

Safety  Precautions  in  the  Oxy-acetylene  Trade.  —  The  ad- 
vantages of  oxy-acetylene  welding  and  cutting  have  led  to  its 
wide  adoption  in  industrial  plants.  As  a  practically  new  trade, 
however,  its  hazards  are  not  yet  well  appreciated.  It  is  well, 
therefore,  to  call  attention  to  certain  precautions  which  should 
be  observed  in  handling  welding  apparatus.  If  portability  is 
desired,  both  the  oxygen  and  the  acetylene  should  be  obtained 
from  storage  cylinders.  A  portable  acetylene  generator  requires 
the  removal  of  either  the  water  or  the  carbide  before  the  generator 
can  be  moved  safely.  Otherwise,  if  the  generator  tips  over,  the 
mixture  of  water  and  carbide  will  generate  large  quantities  of 
gas,  probably  causing  an  explosion. 

Accidents  have  occurred  from  using  an  open-flame  light  when 
cleaning  out  an  acetylene  generator.  It  is  customary  to  wait 
until  the  pressure  gage  indicates  no  gas  in  the  generator  before 
beginning  to  clean  it.  Sometimes  a  small  pocket  of  the  gas  re- 
mains, however,  and  burns  the  workman  when  ignition  takes 
place  from  the  open  flame.  Carbide  will  occasionally  cake  on 
the  sides  of  the  generator,  and,  unless  the  water  is  removed  at 
once,  the  caked  carbide  will  generate  gas  as  it  is  knocked  from 
the  tank,  and  will  ignite  and  burn  the  workman.  A  portable 
incandescent  electric  lamp  should,  therefore,  be  used,  instead  of 
an  open  flame. 

The  tubes  or  hose  connecting  the  torch  with  the  acetylene  and 
oxygen  supply  are  subjected  to  twists,  turns,  and  abrasive  ac- 
tion, causing  minor  leaks,  and  the  fastenings  may  loosen  and 
permit  gas  to  escape.  The  torch  itself  or  sparks  from  the  weld- 
ing will  ignite  the  escaping  gas.  Occasionally,  gas  from  loosened 
fastenings  may  gather  about  the  clothing  of  the  workman,  be- 
come ignited,  and  severely  burn  the  workman.  The  hose 
fastenings  and  the  hose  itself  should,  therefore,  be  frequently 
inspected  for  any  leaks. 

Little,  if  any,  attention  has  been  given  to  the  effect  of  oxy- 
acetylene  welding  upon  health.  The  heat  from  the  flame  is 


250  GENERAL  CONSIDERATIONS 

sufficient  to  vaporize  the  metals,  and,  since  the  workman's 
head  must  be  within  a  foot  or  two  of  the  flame,  he  must  breath  the 
products  of  combustion  unless  protection  is  provided.  A  hel- 
met, with  a  colored  glass  front,  would  afford  this  protection,  as 
well  as  protection  from  the  intense  light. 

Oxygen  is  usually  sold  in  cylinders  under  pressures  up  to  1800 
pounds  per  square  inch.  A  defective  cylinder  may  cause  a  de- 
structive explosion.  To  guard  against  such  accidents,  the  cylin- 
ders should  never  be  stored  in  the  working  room,  but  in  a  special 
room  with  substantial  walls.  Full  tanks  should  not  be  left  in 
places  where  the  direct  rays  of  the  sun  may  strike  them,  or  close 
to  heating  apparatus  or  other  sources  of  heat  which  would  cause 
dangerous  expansion. 

Strength  of  Welded  Forgings.  —  Sometimes  trouble  occurs, 
particularly  in  the  case  of  forged  steel  parts,  from  not  realizing 
that  an  oxy-acetylene  weld  is  really  only  a  casting,  and  that 
even  with  the  best  possible  work  the  weld  will  not  be  as  strong 
as  the  original  piece.  If  a  forged  steel  piece  is  broken  by  care- 
lessness or  accident,  it  may  be  possible  to  weld  it  so  that  it  will 
be  strong  enough,  particularly  if  there  is  space  enough  to  rein- 
force the  weld  sufficiently.  On  the  other  hand,  if  it  has  to  be 
machined  to  the  original  size,  and  if  the  fracture  is  caused  by  the 
part  being  originally  too  light,  the  chances  are  that  unsatisfac- 
tory results  will  be  obtained  in  service.  It  is  doubtful  if  any 
attempt  should  be  made  to  weld  many  kinds  of  steel  forgings. 
This  is  particularly  true  in  the  case  of  alloy  steels,  such  as  vana- 
dium steel,  chrome-nickel  steel,  etc.  These  materials  occur 
usually  in  automobile  parts,  their  use  not  being  frequent  in 
ordinary  machinery.  It  appears  useless  to  weld  such  pieces,  as 
they  cannot  be  made  anywhere  nearly  as  strong  as  they  were  in 
the  first  place.  Particularly  objectionable  is  the  welding  of  cer- 
tain parts  of  an  automobile,  such  as  a  steering  knuckle,  where 
the  spindle  has  broken  off.  Many  such  parts  have  been  welded 
and  held  satisfactorily,  but  it  is  not  recommended  and  should 
not  be  done  until  after  the  customer's  attention  is  called  to  the 
danger,  and  he  has  agreed  to  accept  the  responsibility  for  any 
damage.  Even  then  it  is  advisable  not  to  run  the  risk.  If  it  is 


GENERAL   CONSIDERATIONS  251 

remembered  that  cast  steel  is  never  as  strong  as  rolled  or  forged 
steel,  it  is  hardly  possible  to  use  wrong  judgment  as  to  the  ad- 
visability of  welding.  It  is  better  to  err  on  the  side  of  safety  than 
to  take  chances. 

A  further  reason  for  being  careful  in  welding  steel  is  on  account 
of  the  peculiar  property  of  this  metal,  which  requires  that,  under 
alternating  strains,  a  certain  proportion  of  the  elastic  limit  must 
not  be  exceeded,  otherwise  a  fracture  will  occur  in  the  course  of 
time.  Now  the  elastic  limit  of  cast  steel,  no  matter  how  good,  is 
far  below  the  elastic  limit  of  forged  and  heat-treated  steel, 
particularly  alloy  steel.  Therefore,  a  fracture  will  occur  much 
sooner  in  the  case  of  a  weld  than  in  the  case  of  the  original 
piece,  even  if  the  weld  is  sound.  Much  could  be  done  in  the  way 
of  strengthening  the  weld,  if  it  were  possible  to  heat-treat  it 
properly,  but  this  branch  has  not,  so  far,  been  developed  in  con- 
nection with  welded  parts. 

Tests  on  Strength  of  Welds.  —  With  regard  to  the  strength 
of  welds,  the  author  knows  of  no  comprehensive  tests  that  have 
been  published,  and  does  not  believe  that  any  investigations 
that  have  been  made  are  complete  enough  to  warrant  accurate 
conclusions,  particularly  when  modern  welding  practice  is  con- 
sidered. 

Cast  Iron.  —  In  the  case  of  cast  iron,  it  is  well  known  that  the 
weld  is  stronger  and  less  brittle  than  the  original  material; 
that  is,  as  far  as  any  ordinary  cast  iron  is  concerned.  An 
explanation  of  this  is  to  be  found  in  what  may  be  called  the 
"  anatomy  "  of  the  weld.  It  is  finer  grained,  and,  inasmuch  as  the 
welding-rods  have  to  be  made  of  good  material,  it  is  generally 
of  a  better  quality  than  the  original  casting.  It  is,  therefore, 
hardly  necessary  to  discuss  in  detail  the  strength  of  cast-iron 
welds. 

Steel.  —  With  regard  to  steel,  the  situation  is  very  compli- 
cated. There  are  so  many  different  kinds  of  steel,  and  they  are 
used  for  so  many  different  purposes,  and  are  subjected  to  so 
many  different  kinds  of  strains,  that  it  is  impossible  to  lay  down 
any  general  rule  as  to  the  strength  of  welds  in  this  material.  It 
has  been  claimed  that  oxy-acetylene  welds  are  brittle  and  hard 


252  GENERAL  CONSIDERATIONS 

although  they  may  have  greater  tensile  strength  than  that  of 
the  original  material.  It  is  true  that  in  the  early  days  of  oxy- 
acetylene  welding,  when  torches  did  not  give  as  nearly  a  neutral 
flame  as  they  do  at  the  present  time,  many  welds  were  burnt, 
and  were,  therefore,  brittle  and  hard.  At  the  present  time,  how- 
ever, any  weld  of  this  character  shows  that  the  welder  either 
used  a  poor  torch  or  did  not  know  how  to  handle  it.  Hardness 
and  ductility  are  relative  terms,  and  a  weld  in  a  very  soft, 
ductile,  low-carbon  steel  may  be  harder  than  the  original  ma- 
terial, while  a  weld  made  with  the  same  welding-wire  in  a  much 
harder  steel  of  higher  carbon  may  be  softer  than  the  original 
weld.  In  the  former  case,  the  original  material  may  be  more 
ductile  than  the  weld,  while  the  opposite  may  be  true  in  the 
case  of  a  harder  original  material.  Again,  the  effect  of  the  heat 
on  the  added  material  will  be  approximately  the  same  in  both 
cases.  It  is  not  true,  however,  that  the  effect  of  the  heat  will 
be  the  same  on  the  original  material  in  both  cases.  In  the  case 
of  the  soft  ductile  steel,  the  tensile  strength  of  the  weld  will 
undoubtedly  be  higher  than  that  of  the  original  material,  while, 
in  the  other  case,  the  tensile  strength  will  be  less,  and  it  may 
even  happen,  in  the  second  instance,  that  the  material  just  next 
to  the  weld  will  be  so  badly  damaged  by  the  heat  that  the  test- 
piece  will  break  there,  and  neither  in  the  weld  nor  some  distance 
away  from  it.  In  the  case  of  the  higher  carbon  steels,  there  is 
a  still  different  action  in  that  the  material  next  to  the  weld  and 
in  other  places,  where  the  heat  is  high  enough,  is  decarburized. 
The  extent  of  this  decarburization  varies  with  the  intensity 
of  the  heat  and  the  time  to  which  the  piece  is  subjected  to  it. 
A  higher  temperature  and  longer  continued  heating  remove 
more  carbon.  This  action  is  not  due  to  anything  except  the  heat 
and  the  presence  of  the  oxygen  in  the  air,  and  would  occur  with 
any  method  of  heating.  Another  thing  that  occurs  with  very 
high  carbon  steel,  such  as  tool  steel,  is  the  burning  of  the  original 
metal  in  the  vicinity  of  the  weld.  This  applies  particularly  to 
tool  steel,  and  an  examination  of  many  specimens  microscopi- 
cally indicates  that  it  is  not  possible  to  weld  high-carbon  steel 
without  burning  it.  Of  course,  it  is  possible  that  the  union  may 


GENERAL  CONSIDERATIONS 


253 


be  strong  enough  for  certain  purposes,  but  the  material  next  to 
the  weld  is  not  sound,  and  no  method  of  annealing  or  heat-treat- 
ment will  cure  steel  that  is  really  burnt. 

Ductility  of  Steel  Welds.  —  With  regard  to  the  ductility  of 
steel  welds,  Figs,  i  and  2  show  some  test-pieces  nearly  full  size, 
before  and  after  bending,  the  weld  being  made  in  the  center  of 
the  test-piece.  It  cannot  be  claimed  that  such  welds  are  brittle 
or  lack  ductility.  Fig.  3  shows,  full  size,  a  similar  weld  made 
in  the  same  material  and  flattened  cold.  This  also  shows  that 
a  properly  made  weld  is  ductile.  In  the  particular  cases  shown, 


Fig.  1.   Test  Specimens  showing  Ductility  of  Welded  Joint 

the  test-pieces  broke  about  2\  inches  from  the  weld,  but  the 
material  from  which  they  were  made  was  a  very  low  carbon 
steel  of  47,500  pounds'  tensile  strength;  hence,  it  would  be 
naturally  expected  that  such  material  would  not  break  in  the 
weld.  With  steel  of  about  55,000  pounds'  tensile  strength,  a 
welded  test-piece  will  usually  break  in  the  weld,  giving  a  tensile 
strength  of  about  52,000  pounds.  The  elongation  in  such  cases 
may  run  as  high  as  20  per  cent,  that  of  the  original  material  being 
in  the  neighborhood  of  32  per  cent.  The  elastic  limit  will  be 
about  33,000  pounds,  against  35,000  pounds  in  the  original. 


254  GENEEAL   CONSIDERATIONS 

So  much  depends  upon  the  material  with  which  the  weld  is  made, 
on  the  method  of  making  it,  and  on  the  heat-treatment  after 
it  is  made,  that  it  is  impossible  to  give  any  specific  results. 
All  of  the  published  tests  that  the  author  has  seen  are,  in  his 
opinion,  deficient  in  essential  information.  For  example,  in 
one  report  of  some  tests  made  about  two  years  ago,  calling  the 
average  of  the  original  pieces  100  both  for  tensile  strength  and 
elongation,  the  average  for  the  welds  untreated  in  any  way  was 
only  85  for  tensile  strength  and  22  for  elongation.  The  author's 
belief  is  that  these  welds  were  in  some  way  improperly  made, 
as  he  has  never  obtained  such  low  figures  as  these.  The  lowest 
results  given  are  for  tensile  strength,  about  80  per  cent  of 
the  original,  and  for  elongation,  9.3  per  cent  of  the  original. 


Fig.  2.    View  from  above  of  Test  Specimens  shown  in  Fig.  1 

This  latter  very  low  result  indicates  clearly  that  there  was  a  wide 
variation  in  the  actual  condition  of  the  different  welds,  which 
should  not  exist.  It  is  admitted  that  there  will  be  some  varia- 
tion, but  the  author  has  repeatedly  obtained  results  with  a  maxi- 
mum variation  of  10  per  cent  in  the  elongation,  6  per  cent 
in  the  elastic  limit,  and  5  per  cent  in  the  tensile  strength.  As 
has  been  stated  before,  it  cannot  be  claimed  that  any  weld  is  as 
good  as  the  original  material;  and  particularly  in  the  case  of 
steel,  which  is  generally  used  in  places  where  great  strength  and 
high  physical  qualities  are  required,  great  care  should  be  taken 
and  good  judgment  used  in  selecting  the  method  of  joining. 
There  is  one  thing  that  should  be  carefully  considered,  and  that 
is,  whether  a  welded  piece  is  to  be  subjected  to  alternating 
stresses  or  shock.  This  is  the  worst  condition  to  which  a  weld 


GENERAL  CONSIDERATIONS  255 

can  be  subjected,  and  it  is  well  known  that  a  piece  of  over- 
annealed  steel  will  not  stand  these  stresses  nearly  as  well  as  a 
piece  that  has  been  properly  refined  by  correct  heat-treatment. 
Strength  of  Welds  in  Non-ferrous  Metals.  —  With  regard  to 
the  strength  of  welds  in  other  metals,  the  author  is  not  acquainted 
with  any  conclusive  published  tests,  and  is  unable  to  give  any 
results.  However,  in  a  general  way,  if  the  welds  are  made  care- 
fully with  a  good  torch  and  the  proper  materials,  the  results  will 
usually  be  satisfactory,  as,  in  most  cases,  such  metals  as  brass, 
bronze,  aluminum,  and  copper  are  not  subjected  to  any  great 
stress,  although,  of  course,  there  are  exceptions  to  this;  so  that 
a  weld  in  these  materials  will  usually  be  amply  strong,  even  if 
not  equal  to  the  strength  of  the  original  material.  One  point, 


Fig.  3.   Test  Specimen  bent  Cold,  showing  Ductility  of  Weld 

however,  should  be  noted,  which  is  that,  in  the  case  of  brass- 
and  bronze  castings  subjected  to  pressure,  it  is  good  practice, 
if  not  absolutely  necessary,  that  the  whole  piece  be  annealed  at 
the  proper  temperature  in  order  to  relieve  cooling  strains  caused 
by  the  welding.  What  this  annealing  is  depends  upon  the  alloy, 
and  no  definite  instructions  can  be  given.  The  time  and  tempera- 
ture of  annealing,  and  the  rate  of  cooling  all  have  their  effect, 
and  have  to  be  determined  in  each  case  of  importance. 

Miscellaneous  Applications  of  the  Oxy-acetylene  Flame.  — 
The  oxy-acetylene  flame  is  used  not  only  for  welding  and  cutting 
purposes,  but  also  for  the  rapid  heating  of  machine  parts  for 
various  purposes.  One  of  the  applications  is  for  heating  steel 
for  case-  and  surface-hardening.  ,.It  is  especially  useful  for  so- 


256  GENERAL   CONSIDERATIONS 

called  "local  hardening,"  because  the  oxy-acetylene  flame  fur- 
nishes a  highly  concentrated  and  very  intense  source  of  heat, 
which  permits  of  local  heating  with  excellent  results.  For 
local  hardening,  for  example,  it  is  possible  to  heat  only  that  part 
which  is  to  be  hardened  to  the  required  hardening  temperature, 
quenching  it  in  water  as  usual.  The  other  parts  of  the  object 
which  have  not  been  heated  to  the  hardening  heat  will  remain 
soft  as  before.  The  same  results  as  obtained  by  casehardening 
can  also  be  obtained  by  the  use  of  the  oxy-acetylene  torch.  By 
using  a  well-regulated  flame  to  heat  the  steel,  and  afterwards 
permitting  a  slight  excess  of  acetylene  to  impinge  upon  the  piece 
to  be  case-  or  surface-hardened,  it  is  possible  to  obtain  quickly 
a  carburized  surface  on  the  metal  being  treated,  the  carbon  in 
the  acetylene  gas  furnishing  the  required  carbon  for  caseharden- 
ing. It  is  important,  however,  that  the  inside  tip  of  the  flame 
be  kept  at  a  distance  of  at  least  i  inch  from  the  surface  being 
treated.  If  the  flame  is  regulated  in  this  manner,  the  free 
carbon  liberated  by  the  excess  of  acetylene  is  absorbed  by  the 
metal  while  it  is  kept  at  the  carburizing  temperature  by  the  flame. 
It  has  been  ascertained  by  experiments  that,  if  the  inside  tip  of 
the  flame  is  too  close  to  the  surface  to  be  treated,  it  will  be  trans- 
formed into  a  white  cast  iron,  whereas,  if  the  tip  of  the  flame  is 
kept  at  a  distance  of  from  i  to  i|  inches  from  the  surface,  it  will 
be  evenly  carburized  and  will  assume  on  the  surface  the  proper- 
ties of  tool  steel. 

The  use  of  the  oxy-acetylene  torch  for  casehardening  mild 
steel  should  not  be  confused  with  its  use  for  local  hardening  of 
high-carbon  tool  steel.  In  the  former  case,  the  flame  is  used 
for  carburizing  as  well  as  for  heating,  while,  in  the  latter  case,  it 
is  used  for  obtaining  the  hardening  temperature  only.  In  this 
case,  the  part  of  the  object  that  is  not  to  be  hardened  may  be 
kept  cool  by  immersing  it  in  water,  while  only  that  part  which 
is  to  obtain  a  hardening  heat  is  beyond  the  surface  of  the  water 
and  acted  upon  by  the  oxy-acetylene  flame.  When  the  required 
temperature  has  been  reached,  this  portion  also  is  immersed 
in  the  water,  a  local  hardening  effect  on  the  heated  portion 
thereby  being  secured. 


CHAPTER  XI 
LEAD  BURNING 

LEAD  burning  may  be  denned  as  a  form  of  autogenous  weld- 
ing, whereby  the  parts  to  be  united  are  joined  by  melting  metal 
between  them.  This  molten  metal  is  obtained  by  heating  the 
end  of  a  strip  of  lead  of  the  same  composition  as  that  of  the  lead 
plates  to  be  united.  The  addition  of  metal  at  the  joint  is  not 
actually  necessary,  but  it  serves  to  replace  the  material  that  was 
cut  away  before  welding,  and  the  cutting  away  of  metal  at  the 
point  of  fracture  is  a  desirable  practice,  as  it  enables  the  welder 
to  work  more  rapidly  and  do  better  work.  The  term  "lead 
burning"  is  really  a  misnomer  and  should  never  have  come  into 
use,  because  the  lead  is  not  burned  so  long  as  the  welder  does  his 
work  properly.  It  would  be  just  as  proper  to  call  the  welding  of 
iron  or  steel  with  the  oxy-acetylene  flame  "iron  burning"  or 
"steel  burning,"  as  to  call  the  process  of  welding  lead  by  the 
oxy-hydrogen  flame  "lead  burning."  The  operation  is  essen- 
tially one  of  welding  the  lead  with  heat  furnished  by  the  com- 
bustion of  hydrogen,  and  the  technique  of  the  operation  is  almost 
exactly  the  same  as  that  of  ordinary  oxy-acetylene  welding. 
Lead  burning  may  be  effectively  performed  with  an  oxy-acety- 
lene welding  torch,  and  a  skillful  welder  will  soon  learn  the  art 
of  lead  burning,  using  the  same  torch  with  which  he  welds  iron 
or  steel;  but  great  care  must  be  taken,  because  the  temperature 
of  the  oxy-acetylene  flame  is  really  too  high  for  working  on  lead. 

General  Practice  of  Lead  Burning.  —  This  chapter  is  concerned 
with  the  usual  method  of  lead  burning,  and,  for  this  purpose, 
the  gases  used  in  the  torch  consist  of  hydrogen  under  a  pressure 
of  from  one  to  two  pounds  per  square  inch  and  air  under  about 
the  same  pressure.  The  torch  in  which  the  hydrogen  is  burned 
is  designed  to  mix  the  hydrogen  and  air  in  the  correct  propor- 
tion, and  a  jet  tube  in  the  burner  directs  the  flame  against  the 

257 


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LEAD   BURNING  259 

ing,  and  the  ability  to  do  this,  hour  after  hour  throughout  the 
working  day,  can  only  be  acquired  as  the  result  of  wide  experience. 
Just  before  the  lead  comes  to  the  melting  point,  the  welder  brings 
his  strip  of  lead  or  so-called  " solder  stick"  into  the  flame  and 
heats  a  small  portion  of  it  so  that  a  drop  of  molten  lead  will  fall 
into  the  joint  at  B,  at  the  instant  that  the  temperature  of  the 
lead  at  each  side  of  the  groove  has  been  raised  to  the  melting 
point  and  is  about  to  be  changed  to  the  molten  condition.  At 
the  instant  that  the  drop  of  lead  falls  into  the  groove,  the  flame 
is  whisked  to  one  side  and  the  drop  of  molten  metal  breaks 
through  the  heated  surface  at  eadi  side  of  the  groove,  uniting  with 
the  metal  in  the  plates.  The  welder  carefully  observes  the  falling 
of  the  drop  of  lead  and  its  union  with  the  metal  in  the  plates, 
and  if  there  is  the  least  indication  that  all  the  metal  has  not 
united  properly,  he  applies  the  flame  at  that  point  for  a  sufficient 
length  of  time  to  remelt  the  metal  and  allow  it  to  flow  together. 
An  attempt  has  been  made  at  C  to  show  the  perfect  union  of 
a  drop  of  lead  with  the  metal  in  the  plates.  It  will  be  seen  that 
this  is  quite  different  from  the  well-defined  line  between  the  drop 
of  metal  and  plates  as  shown  at  D  and  E.  The  latter  condition 
results  when  the  temperatures  of  the  drop  of  metal  and  the  metal 
in  the  plates  are  not  the  same  or  where  the  temperature  has  not 
been  raised  sufficiently;  but  at  C  the  temperatures  were  correct, 
with  the  result  that  the  lead  in  the  drop  united  with  the  lead  in 
the  plates  in  such  a  way  that  no  junction  line  can  be  seen.  In 
fact,  there  is  no  line  of  connection  or  anything  that  can  properly 
be  called  a  point,  as  the  metal  has  united  to  form  a  homogeneous 
body.  This  is  the  condition  which  will  be  produced  by  a  skill- 
ful lead  burner.  From  B  to  C  are  shown  several  small  globules 
of  lead  that  have  been  melted  into  the  joint  and  allowed  to  unite 
with  the  lead  plates.  It  will  be  noted  that  these  completely 
fill  the  groove.  If  all  of  the  drops  are  of  the  same  size,  and  are 
deposited  in  a  straight  line,  it  indicates  that  the  work  was  done 
by  a  skillful  lead  burner;  and  although  the  beginner  may  secure 
a  strong  and  perfect  joint  between  the  plates,  it  is  probable  that 
the  drops  of  lead  that  he  deposits  in  the  joint  will  be  of  irregular 
shape  and  size,  and  will  not  be  in  a  straight  line. 


260  LEAD   BURNING 

Starting  the  Lead  Weld.  —  Fig.  2  shows  how  a  joint  may  be 
started,  and  also  illustrates  some  troubles  which  may  be  experi- 
enced by  a  lead  burner.  At  F  the  flame  was  applied  to  the  work 
for  too  long  a  time,  with  the  result  that  some  of  the  lead  G  has 
melted  and  run  out  of  the  joint.  This  must  be  replaced  from  the 
"solder  stick"  and  causes  a  loss  of  both  time  and  material. 
The  hole  shown  at  H  was  caused  by  holding  the  flame  on  one  side 
of  the  joint  too  long,  with  the  result  that  the  metal  melted  and 
flowed  away  at  the  point  /.  This  condition  will  cause  irregu- 
larity in  the  finished  seam  and  remain  as  a  permanent  indication 
that  the  work  was  done  by  a  careless  or  inexperienced  operator. 

It  will  be  noticed  that  at  J  the  edge  of  the  sheet  has  not  been 
melted  back;  it  is  still  in  line  with  the  unwelded  part  of  the  plate 
and  there  is  a  probability  that  a  leak  may  be  found  at  this  point 
when  the  completed  joint  is  tested.  The  most  skillful  welders 
melt  the  edges  of  the  plates  back  far  enough  to  be  sure  that  all 
the  beveled  edges  of  the  metal  have  been  heated  to  the  melting 
point.  It  is  possible  to  heat  the  edges  of  the  plates  so  accu- 
rately that  the  metal  will  unite  with  the  drops  of  lead  without 
actually  melting  back  the  beveled  edges;  but  the  safer  plan  is 
to  melt  the  lead  back  at  each  side  of  the  joint  for  at  least  -£%  inch, 
in  order  to  be  sure  that  a  perfect  union  has  been  obtained. 

Lead  Burning  without  Beveling.  —  Fig.  3  shows  the  result 
of  attempting  to  burn  a  joint  with  square-edged  plates.  This 
method  may  be  employed  on  very  thin  plates,  but  it  is  doubtful 
whether  or  not  a  perfect  joint  will  be  secured.  In  attempting 
to  weld  two  square-edged  plates,  the  lead  burner  starts  at  end 
K  and  must  melt  the  top  edge  of  the  plate  before  the  lower 
edge  can  be  heated.  By  the  time  that  some  point  L  is  reached, 
other  difficulties  will  be  encountered.  One  difficulty  is  in  having 
to  drive  the  heat  down  through  a  layer  of  molten  metal,  in  order 
to  heat  the  plates  to  their  lower  edges,  with  the  result  that  there 
is  likely  to  be  a  large  part  of  the  lower  edges  of  the  plates  which 
has  not  been  properly  joined,  but  where  the  plates  have  been 
beveled  at  the  edges,  as  previously  described,  the  welding  is 
done  at  the  lower  edges  first,  and  a  strong  and  uniform  joint  is 
secured. 


LEAD   BURNING 


261 


Apparatus  Used  for  Lead  Burning.  —  The  apparatus  used  for 
lead  burning  consists  of  a  burner  provided  with  two  lines  of 
rubber  tubing  about  J  inch  in  diameter,  which  connect  the  burner 
with  suitable  sources  of  air  and  hydrogen.  Rubber  tubes  from 
50  to  75  feet  long  are  sometimes  used  in  order  to  give  the  welder 
sufficient  latitude  to  work  inside  of  large  tanks.  Metal  pipes 


Machinery 


Fig.  4.   Cross-sectional  View  of  Hydrogen  Generator 

may  be  used  for  part  of  the  distance,  but  it  will  usually  be  found 
more  satisfactory  to  provide  a  sufficient  length  of  rubber  tubing 
to  reach  from  the  source  of  oxygen  and  hydrogen  to  the  most 
remote  point  at  which  welding  is  to  be  done.  The  hydrogen 
generator  should  be  located  out  of  doors,  because  it  gives  off 
noxious  gases  while  in  operation.  The  hydrogen  may  be  stored 
in  pressure  tubes  and  delivered  through  a  reducing  valve  which 


262  LEAD  BURNING 

will  maintain  the  pressure  between  one  and  two  pounds  per 
square  inch.  The  air  supply  may  be  obtained  by  any  convenient 
method.  A  hand  pump  can  be  used  where  power  is  not  avail- 
able, but,  in  most  cases,  a  small  motor  pump  will  give  satisfac- 
tory results.  A  small  gasoline  engine  will  be  found  satisfactory 
for  driving  the  air  pump,  if  no  other  source  of  power  is  available. 
Hydrogen  Generator.  —  Fig.  4  shows  the  arrangement  of  a 
hydrogen  generator  of  the  type  used  for  lead  burning.  This 
is  usually  constructed  of  i-inch  boards  screwed  together  with  brass 
screws,  as  iron  is  quickly  corroded  by  the  acid  fumes.  The  inside 
of  the  generator  is  covered  with  lead,  and  the  seams  between 
adjacent  lead  plates  should  be  burned  together,  as  the  tin  con- 
tained in  solder  would  be  quickly  attacked  by  the  sulphuric 
acid  used  in  producing  the  hydrogen.  The  generating  appara- 
tus consists  of  two  tanks  located  one  above  the  other;  and  the 
vertical  distance  between  these  tanks  regulates  the  amount  of 
pressure  on  the  hydrogen.  The  two  tanks  A  and  B  are  made 
in  sizes  about  8  by  8  by  24  inches,  and  are  furnished  with  a  lead 
lining  C.  The  lower  tank  has  an  inlet  D  fitted  with  a  screw 
cap  which  may  be  removed  for  charging  the  tank  with  dilute 
sulphuric  acid.  A  similar  opening  is  provided  at  E  for  cleaning 
out  the  tank  and  removing  the  residual  sludge  which  remains 
from  the  spent  chemicals.  The  grating  F  is  made  of  wood  or 
metal  bars  covered  with  lead,  and  this  grating  supports  the  iron 
or  zinc  G,  which  reacts  with  the  sulphuric  acid  to  generate  hydro- 
gen. Valve  H  provides  for  shutting  off  the  flow  of  hydrogen 
when  the  apparatus  is  not  in  use,  and  there  is  a  second  valve 
at  the  burner  that  is  used  for  the  same  purpose;  but  valve  H 
should  always  be  closed  when  it  is  required  to  shut  the  gas  off 
for  a  considerable  period  of  time,  in  order  to  relieve  the  rub- 
ber tubing  from  strain.  The  arrangement  of  the  rubber  tubing 
and  the.  method  of  connection  are  shown  at  /.  A  pipe  /  con- 
nects the  upper  and  lower  compartments  of  the  generator,  the 
entrance  of  pipe  J  into  the  upper  compartment  being  just  flush 
with  the  lead  lining  at  L,  to  which  it  is  joined  by  burning.  It 
will  be  obvious  that  pipe  /  must  be  made  of  lead  and  that  it 
must  also  be  tightly  joined  to  the  lining  of  the  lower  compart- 


LEAD   BURNING  263 

ment  into  which  the  pipe  projects  almost  to  the  bottom,  as 
shown  at  K. 

Operation  of  Generator.  —  The  method  of  operating  the  gen- 
erator may  be  briefly  described  as  follows:  The  iron  or  zinc  G 
is  placed  in  position  on  the  grating  F,  and  clean-out  pipe  E  and 
valve  H  are  tightly  closed.  Sulphuric  acid  diluted  with  water 
is  next  poured  into  the  generator  through  opening  D  until  tank 
A  has  been  filled  within  about  2  inches  of  the  top.  The  intro- 
duction of  the  acid  should  be  done  as  rapidly  as  possible,  after 
which  opening  D  is  closed  immediately,  as  hydrogen  is  lib- 
erated the  instant  the  acid  comes  into  contact  with  the  metal 
at  G.  As  the  gas  is  generated,  it  rises  through  the  liquid  and 
soon  fills  the  space  at  the  top  of  tank  A .  Continued  liberation  of 


Fig.  5.    Modern  Lead-burning  Torch  which  uses  Acetylene  and  Air 

gas  causes  pressure  to  be  set  up  in  tank  A ,  which  results  in  forc- 
ing a  portion  of  the  liquid  up  through  pipe  /  into  upper  compart- 
ment B  of  the  generator.  In  case  none  of  the  gas  is  drawn  off 
through  valve  H,  more  and  more  of  the  liquid  will  be  driven  up 
into  tank  B  until  the  level  of  the  liquid  in  tank  A  has  fallen  below 
the  level  of  grating  F,  with  the  result  that  metal  G  is  removed 
from  contact  with  the  acid,  which  causes  the  generation  of  hydro- 
gen to  be  automatically  stopped. 

If,  however,  any  of  ihe  metal  G  falls  through  the  grating  into 
the  bottom  of  tank  A,  generation  of  hydrogen  will  continue 
until  the  piece  of  metal  is  entirely  oxidized.  This  continued 
generation  of  hydrogen  will  result  in  driving  the  liquid  up  through 
pipe  /  into  upper  compartment  B  until  the  lower  end  of  pipe  J 
is  uncovered.  This  will  allow  hydrogen  to  escape  through  pipe 
/  into  the  upper  compartment  of  the  generator,  from  which 


264 


LEAD  BURNING 


it  escapes  through  vent  M  provided  for  that  purpose.  Vent  M 
also  provides  for  the  escape  or  entrance  of  air  as  the  liquid  enters 
or  leaves  compartment  B.  In  this  way,  pressure  is  maintained 
upon  the  hydrogen,  the  amount  of  pressure  being  determined 
by  the  difference  of  level  of  the  liquid  in  compartments  A  and  B 
of  the  generator.  The  arrangement  is  such  that  the  pressure 


Fig.  6.   Complete  Lead-burning  Outfit  in  which  Air  and 
Acetylene  are  used 

is  usually  slightly  over  one  pound  per  square  inch.  When  all 
of  the  liquid  is  forced  up  into  compartment  B,  the  pressure  will 
naturally  be  somewhat  higher  than  it  is  when  most  of  the  liquid 
is  in  compartment  A,  but  the  maximum  variation  is  not  more 
than  8  or  9  ounces,  and  exerts  little  effect  .upon  the  action  of 
the  flame  at  the  welding  point.  When  hydrogen  is  drawn  off 
from  tank  A,  especially  if  it  is  drawn  off  faster  than  the  gas  is 


LEAD   BURNING  265 

being  generated,  liquid  flows  down  through  pipe  /  into  the  lower 
compartment,  A,  so  that  the  action  of  the  generator  is  entirely 
automatic  as  long  as  the  supply  of  metal  G  and  dilute  sulphuric 
acid  lasts.  Vent  tube  M  may  be  closed  with  a  pipe  cap  through 
which  several  small  holes  have  been  drilled,  to  prevent  large 
pieces  of  dirt  and  insects  from  finding  their  way  into  the  tanks. 

Modern  Lead-burning  Outfits.  —  Since  the  development  of 
the  method  of  generating  acetylene  by  the  chemical  reaction  of 
calcium  carbide  and  water,  the  apparatus  used  for  lead  burning 
has  been  materially  simplified  by  the  substitution  of  acetylene 
gas  for  hydrogen.  In  most  modern  lead-burning  outfits,  the 
blower  or  pump  for  supplying  the  necessary  amount  of  air  has 
also  been  dispensed  with  and  a  tank  of  compressed  air  is  sub- 
stituted, which  has  a  suitable  reducing  valve  to  regulate  the 
pressure.  Figs.  5  and  6  illustrate  a  modern  lead-burning  torch 
and  a  complete  lead-burning  outfit,  respectively,  these  equip- 
ments being  of  the  type  manufactured  by  the  Prest-O-Lite  Co. 
Fig.  6  shows  a  regular  oxy-acetylene  welding  outfit  provided 
with  a  bench  regulating  block,  acetylene  and  oxygen  tanks, 
and  suitable  reducing  valves.  To  change  this  outfit  for  use  in 
lead  burning,  the  oxygen  cylinder  is  replaced  by  a  tube  of  com- 
pressed air,  or  the  torch  may  be  supplied  with  air  by  any  con- 
venient method.  The  ordinary  welding  torch  may  be  used, 
or  a  more  simple  torch  may  be  employed.  Fig.  5  shows  a  torch 
of  simple  design,  especially  intended  for  use  in  lead-burning 
operations;  it  is  not  provided  with  the  adjusting  valve  required 
on  the  oxy-acetylene  torch,  and  the  combustion  of  acetylene 
is  effected  by  supplying  air  to  the  torch  in  place  of  pure  oxygen. 
This  reduces  the  intensity  of  the  temperature  of  the  flame  to 
such  a  degree  that  it  is  suitable  for  melting  lead  without  causing 
excessive  oxidation  or  danger  of  melting  the  metal  too  rapidly. 


CHAPTER  XII 
CUTTING  METALS  WITH  THE  OXIDIZING  FLAME 

To  the  general  public,  the  method  of  cutting  steel  by  the 
use  of  the  oxy-acetylene  or  the  oxy-hydrogen  torch  is  probably 
better  known  than  the  operation  of  welding.  It  certainly  is 
more  spectacular,  on  account  of  its  application  to  the  wrecking 
of  burned  steel  frame  buildings,  obsolete  bridges,  etc.,  which  is 
work  that  is  generally  done  in  view  of  a  large  number  of  people. 
As  a  general  rule,  the  cost  of  cutting  metal  by  this  process  is  less 
than  by  any  other  means,  and,  in  some  cases,  the  saving  effected 
is  very  great.  For  instance,  in  armor-plate  plants,  it  is  common 
practice  to  cut  1 6-inch  armor  plate  at  the  rate  of  nineteen  feet 
per  hour,  a  speed  which  cannot  be  attained  by  any  other  process. 
This  is  done  at  an  expense  so  low  that  it  is  not  comparable  with 
the  cost  when  done  by  ordinary  machines.  The  time  element 
enters  largely  into  such  cases,  as  well  as  the  fact  that  irregular 
shapes  can  be  produced  as  readily  as  straight  lines. 

Principle  of  Method.  —  The  principle  of  oxy-acetylene  or  oxy- 
hydrogen  metal  cutting  is  based  on  the  fact  that,  if  a  piece  of 
steel  or  iron  is  brought  to  a  red  heat  and  a  jet  of  pure  oxygen 
is  turned  against  it,  the  metal  will  be  oxidized  or  will  burn. 
It  is  frequently  thought  that  the  process  is  one  of  melting  the 
metal.  This  is  not  correct,  as  the  metal  is  simply  burned  away 
where  the  jet  of  pure  oxygen  comes  in  contact  with  it.  .In  other 
words,  it  is  simply  an  intensified  form  of  oxidation  or  rusting. 

The  Cutting  Torch.  —  The  ordinary  cutting  torch  consists 
of  a  heating  jet  using  oxygen  and  acetylene,  oxygen  and  hydro- 
gen, oxygen  and  coal  gas,  or,  in  fact,  any  other  gas  which,  when 
combined  with  oxygen,  will  produce  heat.  By  the  use  of  this 
heating  jet,  the  metal  is  first  brought  to  a  sufficiently,  high  tem- 
perature, and  an  auxiliary  jet  of  pure  oxygen  is  then  turned  onto 
the  red-hot  metal,  when  the  action  just  referred  to  takes  place. 

266 


CUTTING  WITH  OXIDIZING  FLAME  267 

The  early  form  of  torch  for  cutting  was  generally  an  ordinary 
welding  torch  with  an  extra  tube  carrying  the  auxiliary  oxygen 
at  the  necessary  pressure,  which  was  clamped  to  the  welding 
torch  when  it  was  desired  to  cut.  Of  course,  the  cutting  jet  has 
to  follow  the  welding  jet,  and,  hence,  such  torches  were  unsatis- 
factory, because  it  was  necessary  to  turn  them  around  when 
the  direction  of  cutting  was  changed.  It  was  also  difficult  to 
bring  the  cutting  jet  as  close  to  the  welding  jet  as  desirable. 
Later  the  auxiliary  jet  of  oxygen  was  placed  between  two  or  more 
welding  jets  in  one  tip,  so  that  no  matter  what  the  direction  of 
the  cut,  the  torch  could  be  held  in  the  same  position,  making  it 
more  convenient  for  the  operator  and  consuming  much  less  time. 

Hand  and  Machine  Cutting.  —  The  operation  of  cutting  is 
one  that  is  very  readily  learned.  The  difficulty  increases  con- 
siderably with  the  thickness  of  the  metal,  but,  for  all  ordinary 
thicknesses,  a  few  hours'  instruction  will  enable  good  and  eco- 
nomical work  to  be  done.  It  is  impossible,  however,  to  cut  very 
smoothly  by  hand,  as  the  torch  cannot  be  held  sufficiently 
steady  to  do  work  which  requires  great  accuracy.  Cutting 
machines  have,  therefore,  been  produced  which  not  only  cut 
straight  and  clean,  but  also  make  a  very  narrow  kerf,  which  im- 
plies a  considerable  reduction  of  the  oxygen  used,  as  compared 
with  that  consumed  in  hand  cutting. 

Cleaning  Work  to  be  Cut.  —  The  principal  difficulty  encoun- 
tered in  cutting  is  the  presence  of  scale,  rust,  paint,  or  other 
foreign  matter,  which  will  not  burn,  or  which  interferes  with  the 
passing  away  of  the  slag  or  oxide  formed  during  the  process.  It 
is,  therefore,  advisable,  and  in  many  cases  absolutely  necessary, 
to  remove  these  substances  before  doing  the  work.  For  example, 
in  cutting  up  old  boilers  in  a  district  in  which  the  water  contains 
lime  or  other  impurities,  it  is  almost  certain  that  the  inside  of 
the  boiler  sheets  will  be  coated  'with  scale.  This  scale  must 
either  be  removed  by  pounding  the  outside  of  the  boiler  with  a 
sledge  at  the  points  where  the  cuts  are  to  be  made,  or  it  must  be 
chipped  off  from  the  inside.  In  the  case  of  bridges  with  several 
heavy  coats  of  paint,  it  is  sometimes  necessary  to  remove  part 
of  it  by  burning  off  with  an  ordinary  gasoline  torch,  or  by  some 


268  CUTTING   WITH  OXIDIZING  FLAME 

other  method.  Not  only  is  time  saved  by  doing  this,  but  the 
consumption  of  oxygen,  which  is  very  much  greater  in  cutting 
than  in  welding,  is  greatly  reduced.  Without  exception,  it 
pays  to  take  the  precaution  of  removing  such  foreign  matter. 

Procedure  in  Cutting.  —  In  cutting  a  comparatively  thin  piece, 
say,  \  inch  thick,  a  beginning  can  be  made  at  the  top  and  edge  of 
the  piece  by  holding  the  heating  flame  at  that  point,  and,  as 
soon  as  the  metal  becomes  red-hot,  turning  on  the  auxiliary  jet 
of  oxygen.  The  thickness  is  not  sufficient  to  prevent  the  slag 
from  being  blown  out  through  the  bottom  of  the  cut,  which  is 
necessary  in  all  cases.  It  is  evident,  however,  that,  in  the  case 
of  a  somewhat  thicker  piece,  it  would  be  advisable  to  begin  at 
the  bottom  of  the  edge  instead  of  at  the  top,  so  that  the  slag 
would  be  sure  to  be  blown  out  and  fall  through  easily.  It  is 
apparent  that  the  thicker  the  piece,  the  higher  must  be  the 
pressure  of  the  auxiliary  jet  of  oxygen  to  force  out  the  slag.  It 
will  also  be  clear  that  unless  the  slag  is  kept  in  a  melted  condition, 
it  will  clog  the  bottom  of  the  slot  and  stop  the  proper  action  of 
the  torch. 

Any  lack  of  continuity  in  the  piece  being  cut,  such  as  a  blow' 
hole  in  a  steel  casting,  will  make  it  impossible  to  cut  through  the 
piece.  This  is  the  reason  why  it  is  more  difficult  to  cut  through 
two  or  more  pieces  of  sheet  steel  riveted  together  than  through 
a  single  piece  of  the  same  thickness.  The  mill  scale  on  steel 
sheets  is  not  generally  removed  when  they  are  riveted  together 
and  this  breaks  the  continuity  of  the  metal  in  the  joint.  It  has 
been  found  possible,  however,  to  cut  as  many  as  twelve  or  four- 
teen pieces  of  material,  J  inch  thick,  if  the  scale  is  cleaned  off 
and  the  pieces  clamped  together  tightly.  This  can  be  done  by 
hand  only  with  difficulty,  although  it  is  readily  done,  and  a 
smooth,  clean,  and  uniform  cut  obtained,  when  the  work  is  done 
on  the  "oxy  graph"  or  a  similar  power-driven  machine.  The 
possibility  of  cutting  a  number  of  pieces  at  the  same  time  reduces 
the  expense  of  such  work  materially,  and  makes  profitable  some 
operations  which,  if  they  had  to  be  performed  on  single  sheets, 
could  not  be  done  economically  on  account  of  the  high  cost  of 
labor  and  gases. 


CUTTING  WITH  OXIDIZING  FLAME  269 

Rules  for  the  Operation  of  Cutting  Torch.  —  When  starting  a 
cut,  the  steel  is  first  heated  by  the  welding  flame;  then  the  jet 
of  pure  oxygen  is  -turned  on.  The  flame  should  be  directed  a 
little  inward,  so  that  the  under  part  of  the  cut  is  somewhat  in 
advance  of  the  upper  surface  of  the  metal.  This  permits  the 
oxide  of  iron  produced  by  the  jet  to  readily  fall  out  of  the  way. 
If  the  flame  were  inclined  in  the  opposite  direction  or  in  such  a 
way  that  the  cut  at  the  top  were  in  advance,  the  oxide  of  iron 
would  accumulate  in  the  lower  part  of  the  kerf  and  prevent  the 
oxygen  from  attacking  the  metal.  The  torch  should  be  held 
steadily  and  with  the  cone  of  the  heating  flame  just  touching  the 
metal.  When  accurate  cutting  is  necessary,  some  method  of 
mechanically  guiding  the  torch  should  be  employed. 

Thickness  of  Metal  that  can  be  Cut.  —  The  maximum 
thickness  of  metal  that  can  be  cut  by  high-temperature  flames 
depends  largely  upon  the  gases  used  and  the  pressure  of  the  oxy- 
gen; the  thicker  the  material,  the  higher  the  pressure  required. 
When  using  the  oxy-acetylene  flame,  it  might  be  practicable  to 
cut  iron  or  steel  up  to  7  or  8  inches  in  thickness,  whereas,  with 
the  oxy-hydrogen  flame,  the  thickness  could  probably  be  in- 
creased to  20  or  24  inches.  The  oxy-hydrogen  flame  will  cut 
thicker  material  principally  because  it  is  longer  than  the  oxy- 
acetylene  flame  and  can  penetrate  to  the  full  depth  of  the  cut, 
thus  keeping  all  the  oxide  in  a  molten  condition  so  that  it  can 
easily  be  acted  upon  by  the  oxygen  cutting  jet.  A  mechanically- 
guided  torch  will  cut  thick  material  more  satisfactorily  than  a 
hand-guided  torch,  because  the  flame  is  directed  straight  into  the 
cut  and  does  not  wabble,  as  it  tends  to  do  when  the  torch  is  held 
by  hand.  With  any  flame,  the  cut  is  less  accurate  and  the  kerf 
wider,  as  the  thickness  of  the  metal  increases.  When  cutting 
light  material,  the  kerf  might  not  be  over  TV  inch  wide,  whereas, 
for  heavy  stock,  it  might  be  J  or  f  inch  wide. 

Metals  that  can  be  Cut.  —  Only  wrought  iron  and  steel  can 
be  cut  by  the  oxy-acetylene  flame.  An  appreciation  of  the  real 
action  which  takes  place  during  the  cutting  of  iron  or  steel  will 
make  clear  why  cast  iron  and  other  metals  cannot  be  cut.  If 
a  very  thin  strip  of  steel,  such  as  a  watch  spring,  is  heated  red- 


270  CUTTING  WITH  OXIDIZING  FLAME 

hot  and  plunged  into  a  jar  of  pure  oxygen,  the  steel  will  imme- 
diately take  fire  and  burn,  and,  if  there  is  a  sufficient  amount  of 
oxygen,  the  burning  will  continue  until  the  steel  is  consumed. 
Again,  if  a  piece  of  steel  is  heated  red-hot  and  kept  at  this 
temperature,  a  simple  jet  of  oxygen  will  cut  through  it,  the 
requirements  for  cutting  being  that  the  metal  be  brought  to 
a  sufficiently  high  temperature  to  combine  with  the  oxygen 
rapidly. 

The  other  essential  feature  of  the  process  is  the  removal  of 
the  oxide  which  results  from  the  combining  of  the  oxygen  with 
the  metal.  In  the  case  of  ordinary  low-carbon  steel,  the  melting 
point  of  the  metal  is  higher  than  the  melting  point  of  the  oxide, 
and,  as  the  action  of  the  cutting  is  largely  self-sustaining,  that 
is,  the  heat  from  the  melted  slag  materially  helps  to  raise  the 
temperature  of  the  steel  in  contact  with  it  to  the  necessary  point 
for  the  continuation  of  the  process,  it  appears  that  the  slag  will 
flow  away  without  mixing  with  the  metal. 

High-carbon  Steel  and  Cast  Iron.  —  With  high-carbon  steels, 
the  melting  point  of  which  is  very  nearly  that  of  the  oxide,  there 
is  a  considerable  tendency  for  the  metal  to  melt  under  the  heat 
of  the  slag  and  for  the  two  to  mix,  preventing  the  oxygen  from 
reaching  the  clean  metal,  as  it  does  when  the  slag  flows  away 
smoothly.  However,  high-carbon  steel  can  be  cut,  but,  if  an 
attempt  is  made  to  cut  a  piece  of  chilled  iron,  it  will  be  found 
that,  while  the  action  starts,  it  will  not  continue;  that  is,  the 
metal  will  not  fly  out  of  the  cut  in  sparks,  but  will  drop  in  little 
globules  of  melted  metal.  There  is  no  graphite  in  chilled  cast 
iron,  all  of  the  carbon  being  in  the  combined  state,  while,  in  ordi- 
nary cast  iron,  part  of  the  carbon  is  in  the  form  of  graphite,  which 
interferes  with  the  action  to  an  even  greater  extent  than  is 
the  case  with  drilled  iron,  on  account  of  the  lack  of  continuity 
of  the  cast-iron  grains  between  which  the  graphite  is  located; 
hence,  cast  iron  cannot  be  cut  by  the  oxy-acetylene  torch. 

Malleable  Iron.  —  If  malleable  iron  be  tested  with  a  cutting 
torch,  it  will  be  found  that  a  white-heart  casting,  which  is  really 
a  low-grade  steel,  will  readily  cut,  because  the  percentage  of 
carbon  is  lower  than  in  the  case  of  the  chilled  iron  of  which  it 


CUTTING  WITH  OXIDIZING  FLAME 

was  made;  while  if  a  rather  thick  black-heart  casting  be  tested, 
with  an  outer  skin  in  which  the  percentage  of  carbon  is  low  enough 
to  entitle  it  to  be  called  steel,  and  a  center  containing  the  same 
percentage  of  carbon  as  the  chilled  iron  of  which  it  was  made 
(although  its  form  has  been  changed  to  that  of  temper  instead  of 
combined  carbon) ,  it  will  be  found  impossible  to  cut.  However, 
thin  sections  of  black-heart  malleable  iron  may  be  cut  with 
satisfactory  results.  It  should  be  understood,  however,  that  the 
edges  of  the  cut  are  not  smooth,  and  that  the  action  in  the  center 
of  the  piece  is  more  that  of  melting  than  of  cutting.  For  the 
results  desired,  however,  these  imperfections  may  be  immaterial. 
Sections  that  can  be  cut  with  good  results  are  not  over  f  inch 
thick,  and  generally  not  over  J  inch. 

Different  Gases  Used.  —  The  use  of  the  cutting  process  has 
been  extended  to  exceedingly  thick  sections,  particularly  in  the 
case  of  armor  plate,  as  already  referred  to.  As  the  oxy-acetylene 
flame  is  much  shorter  than  the  oxy-hydrogen  flame,  and  as  it  is 
necessary  to  keep  the  slag  in  a  melted  condition,  the  longer  flame 
is  preferable,  so  that,  for  all  heavy  cutting,  hydrogen  is  used 
rather  than  acetylene.  With  a  more  general  introduction  of 
electrolytic  plants  for  the  production  of  oxygen,  the  use  of  the 
oxy-hydrogen  flame  for  cutting  may  be  expected  to  develop  at 
a  rapid  rate,  as  hydrogen,  in  this  case,  may  be  considered  as  a 
by-product.  It  also  has  the  advantages  of  being  free  from 
danger  when  compressed  to  any  pressure,  and  of  being  readily 
handled  in  tanks  of  the  same  light  weight  as  oxygen  tanks. 
Coal  gas  or  ordinary  illuminating  gas,  being  largely  composed 
of  hydrogen,  can  also  be  used  with  very  satisfactory  results  for 
cutting,  and,  in  one  case  at  least,  it  is  used  exclusively,  being  much 
cheaper  than  either  acetylene  or  hydrogen.  For  the  best  results, 
however,  each  of  these  gases  requires  a  torch  with  the  openings 
properly  proportioned  and  different  from  those  for  the  other  gases. 

Temperature  of  the  Oxygen.  —  One  very  important  factor 
in  the  cost  of  cutting  is  the  temperature  of  the  oxygen  in  the  cut- 
ting jet.  Anyone  who  has  handled  oxygen  tanks  in  cold  weather 
knows  that  when  the  valve  is  open,  and  oxygen  is  allowed  to 
escape  at  a  fairly  rapid  rate,  the  valve  body  and  other  parts  in 


272  CUTTING  WITH  OXIDIZING  FLAME 

the  vicinity  become  coated  with  snow  or  ice  formed  by  the  con- 
densation of  the  moisture  in  the  surrounding  air.  This  is  caused 
by  the  heat  absorbed  from  these  parts  by  the  expansion  of  the 
gas.  It  is  evident  that  under  such  conditions  the  issuing  gas 
is  very  cold,  and,  when  it  is  used  in  cutting,  the  tendency  is  to 
cool  the  slag  and  metal  and  delay  the  operation  of  the  process. 
It  would  appear  to  be  very  easy  to  place  a  small  steam  coil  around 
the  head  of  the  torch  through  which  the  oxygen  used  for  cutting 
would  pass,  thus  preheating  it.  In  fact,  such  torches  have  been 
constructed,  although,  as  far  as  the  author  knows,  they  are  not 
in  use  in  the  United  States;  an  increase  in  cutting  speed  of  from 
15  to  25  per  cent  is  claimed  for  them.  In  the  case  of  large 
cutting,  the  oxygen  could  be  preheated  in  a  special  heater  in 
the  same  way  as  is  often  done  with  compressed  air. 

Effect  of  Heat  on  Steel.  —  What  effect  has  the  heat  from  cut- 
ting on  the  steel  in  the  vicinity  of  the  cut?  This  point  arises 
particularly  in  the  case  of  high-carbon  s.teel  used  for  dies,  a  large 
number  of  these  now  being  cut  on  automatic  machines,  par- 
ticularly where  the  shape  of  the  die  is  irregular.  It  can  be  stated 
with  perfect  confidence  that  no  change  occurs  as  far  back  as  to 
injure  the  steel  for  this  purpose,  for  while  there  is  a  slight  decar- 
burization  of  the  steel,  the  depth  to  which  it  penetrates  is  less 
than  the  amount  removed  in  finishing  the  die.  An  examination 
of  annealed  pieces  under  the  microscope  shows  this  to  be  the 
case,  the  structure  being  uniform  after  the  annealing  treatment, 
except  for  a  distance  of  less  than  0.020  inch  from  the  cut  surface. 
The  change  in  the  structure  should  preferably  be  remedied  by 
annealing  from  above  the  recalescence  point  after  the  cutting 
is  done,  because  the  change  in  structure  is  always  accompanied 
by  some  strain  which  would  possibly  cause  trouble  later  by  dis- 
torting the  die  when  hardening.  Of  course,  no  good  diemaker 
would  think  of  hardening  a  piece  of  steel  without  removing  the 
surface  for  at  least  -%%  inch  to  take  off  the  decarburized  portion. 
The  same  condition  —  and  no  worse  —  exists  where  oxy-acetylene 
cutting  has  been  employed. 

Application  of  Oxy-acetylene  Cutting  Torch.  —  An  interesting 
application  of  the  oxy-acetylene  cutting  torch  is  shown  in  Fig.  i. 


CUTTING  WITH  OXIDIZING  FLAME 


273 


This  illustration  is  a  reproduction  of  a  photograph  taken  in 
the  basement  of  the  Warren  Telephone  Exchange  at  Syracuse, 
N.  Y.  The  underground  lead  cables  carrying  the  wires  from  the 
city  telephones  into  the  exchange  enter  from  the  street  first  into 
a  manhole,  which  extends  underneath  the  sidewalk  to  the  wall  of 


Fig.  1.    Oxy-acetylene  Torch  being  used  for  Cutting  away  Iron 
Armor  of  Lead-covered  Telephone  Cables 

the  building,  and  from  there  into  the  exchange  room,  the  cables 
being  encased  in  3-inch  iron  pipes.  An  increase  in  the  capacity 
of  the  exchange  made  an  enlargement  of  the  manhold  necessary. 
At  this  time  it  became  also  necessary  to  remove  the  iron  cas- 
ings from  the  lead  cables,  so  that  the  latter  could  be  bent  and 


274  CUTTING  WITH  OXIDIZING  FLAME 

rearranged  to  make  room  for  new  ones.  This  difficult  work  was 
accomplished  by  the  oxy-acetylene  cutting  torch,  without 
damaging  the  lead  cables  underneath.  This  at  first  would 
appear  to  be  an  almost  impossible  proposition,  as  the  melting 
point  of  lead  is  about  620  degrees  F.,  while  that  of  the  pipe  would 
be  about  2500  degrees  F.,  the  oxy-acetylene  flame  itself  having 


Fig.  2.   Cutting  Off  Steel  Sheet  Piling  with  Oxygen  Cutting  Torch, 
showing  Portable  Apparatus 

a  temperature  of  over  6000  degrees  F.     The  method  used  was 
as  follows: 

A  copper  shield  about  six  feet  long  was  slipped  in  between 
the  cable  and  the  casing;  then  the  casing  was  cut  around  with  the 
torch  for  a  short  distance  and  at  a  safe  distance  from  the  inner 
end  of  the  shield,  so  as  not  to  allow  the  flame  to  come  too  near  to 
the  lead  cable;  the  casing  was  then  rolled  over  a  small  amount, 
the  shield  readjusted,  and  another  cut  taken.  This  was  contin- 
ued until  the  casing  was  cut  all  the  way  around;  it  was  then  slid 


CUTTING  WITH  OXIDIZING  FLAME  275 

back  on  the  cable  and  split  in  two  lengthwise,  allowing  the  pieces 
to  be  removed.  The  reason  for  making  the  shields  of  copper 
is  that  the  oxygen  cutting  jet,  as  already  mentioned,  will  only 
cut  wrought  iron  and  steel,  and  does  not  have  any  cutting  effect 
on  copper. 

Cutting  Metal  under  Water.  —  A  German  engineer  has 
designed  a  burner  which  makes  it  possible  to  use  the  oxy-hy- 
drogen  flame  for  cutting  metals  under  water.  The  burner 
consists  of  a  bell-shaped  head  which  is  screwed  onto  an  ordinary 
burner  and  which  allows  the  flame  to  continue  to  burn  below 
the  water  in  a  supply  of  compressed  air.  This  process  has  been 
so  improved  of  late  that  the  cutting  of  metals  under  water  is 
claimed  to  be  effected  almost  as  quickly  as  above  the  surface. 
At  tests  made  with  the  new  apparatus  at  the  harbor  at  Kiel, 
before  prominent  engineers  and  representatives  of  the  German 
government,  a  diver  went  down  into  the  sea  to  a  depth  of  about 
1 6  feet,  and,  after  boring  a  hole  into  an  iron  bar  2\  inches  square, 
cut  off  the  bar  in  about  thirty  seconds.  An  iron  sheet  f  inch 
thick  was  drilled  through  and  cut  for  a  distance  of  one  foot  in 
ninety  seconds. 

Example  of  Metal  Cutting.  —  Fig.  2  illustrates  the  use  of  the 
cutting  torch  for  cutting  off  steel  sheet  piling.  This  work  is 
done  with  rapidity,  and  is  a  very  spectacular  performance.  In 
the  case  of  cutting,  the  combustion  of  the  steel  materially  raises 
the  temperature  and  assists  in  the  work.  This  was  pointed 
out  by  Chevalier  C.  de  Schwarz  in  a  paper  read  before  the  May, 
1906,  meeting  of  the  Iron  and  Steel  Institute,  and  it  gives  one 
a  startling  idea  of  the  power  of  the  oxygen  cutting  flame  when 
the  concentration  of  the  heat  units  produced  is  known.  Burning 
one  pound  of  acetylene  with  oxygen  produces  from  18,250  to 
21,500  B.T.U.  The  mean  value  may  be  taker  as  about  19,750 
B.T.U.  per  pound,  and  the  number  of  cubic  feet  at  atmospheric 
pressure  at  about  14 J.  Now,  the  burning  of  one  pound  of  steel 
with  oxygen  produces  approximately  2970  B.T.U.,  but,  at 
atmospheric  pressure,  one  pound  of  acetylene  gas  fills  6750 
times  the  space  of  one  pound  of  steel;  hence,  the  intensity  of 
the  heat  with  perfect  combustion  of  the  steel  in  oxygen  will  be, 


276 


CUTTING   WITH   OXIDIZING   FLAME 


theoretically,  — —  =  1015  times  the  intensity  of  heat 

19,750 

of  the  oxy-acetylene  flame.  As  a  matter  of  fact,  this  enormous 
temperature  is  not  even  remotely  approached,  because  the  metal 
dissolves  at  a  far  lower  temperature  and  passes  off  in  sparks, 
which  are  speedily  cooled  by  the  atmosphere. 

Cost  of  Cutting  Metals  with  the  Oxy-acetylene  and  Oxy- 
hydrogen  Flame.  —  The  following  figures  will  give  an  idea  of 

Approximate  Cost  of  Machine  Cutting 
Oxygen  at  3  cents  per  cubic  foot,  acetylene  at  i  cent  per  cubic  foot 


Pressure  in 

Cubic  Feet  of  Gas 

No.  of 
Cutting 
Tip 

Thick- 
ness of 
Steel, 
Inches 

Pounds 

per  Foot  of  Cut 

Inches 
Cut  per 
Minute 

Cost  of 
Gas  per 
Foot  of 
Cut 

Oxygen 
for 
Cutting 

Oxygen 
for 
Heating 

Oxygen 

Acety- 
lene 

2 

1 

10 

4 

0.40 

0.086 

24 

$Q.OI3 

2 

£ 

2O 

4 

0.91 

0.15 

15 

0.029 

2 

4 

30 

4 

1.16 

0.15 

15 

0.036 

2 

I 

30 

4 

1-45 

0.172 

12 

0.045 

2 

ii 

40 

4 

2.64 

0.192 

8 

0.081 

3 

i   . 

20 

5 

1.25 

0.27 

18 

0.040 

3 

ij 

3° 

5 

2.40 

0.38 

12 

0.076 

3 

2 

40 

5 

2.96 

0.38 

12 

0.093 

3 

3 

50 

5 

5-37 

0-57 

8 

0.167 

4 

3 

40 

5 

7-23 

0-75 

8 

0.224 

4 

4 

50 

5 

9.70 

0.8o 

7 

0.299 

4 

5 

60 

5 

15.00 

I.OO 

5 

0.460 

4 

6 

70 

6 

21.09 

1.50 

4 

0.648 

4 

7 

80 

6 

25.00 

1.50 

4 

0.765 

4 

8 

90 

6 

28.50 

1-50 

4 

0.870 

4 

9 

100 

6 

43.20 

2.OO 

3 

1.311 

the  cost  of  cutting  metals  by  the  processes  described.  Assuming 
oxygen  at  3  cents  per  cubic  foot  and  acetylene  at  i  cent  per  cubic 
foot,  2  feet  of  |-inch  thick  steel  can  be  cut  per  minute  at  a  cost 
of  1.3  cent  per  foot,  and  i  foot  of  i|-inch  thick  steel  can  be  cut 
per  minute  at  a  cost  of  7.6  cents  per  foot.  This  cost  is  for  gas 
alone;  the  cost  of  labor  must,  of  course,  be  added.  The  figures 
given  are  for  machine-guided  torches.  When  cutting  with  a 
hand-guided  torch,  the  gas  consumption  will  be  approximately 
one-third  more  and  the  number  of  feet  cut  per  hour,  one-third 
less,  than  when  the  torch  is  mechanically  guided  by  a  special 


CUTTING   WITH   OXIDIZING   FLAME 

Gas  Consumption  when  Cutting  with  Oxy-hydrogen  Flame 

(American  Oxhydric  Co.) 


277 


Cutting  with  Machine  Torch 

Gas  Consumption  in  Cubic  Feet 

Cost  of  Gases,  Oxy- 

Time 

gen  at  2\  cents, 
Hydrogen  at 

Thick- 

ii  cent 

Width 

e   /~«.,4. 

ness, 
Inches 

Seconds 

Minutes 

Per  Lineal  Inch, 

Per  Lineal  Foot, 
Cut 

Per 

Per 

oi  Cut, 
Inch 

£dh 

Foot 

u 

Lineal 
Inch 

Lineal 
Foot 

Oxy. 

Hyd. 

Oxy. 

Hyd. 

i 

5-0 

I 

0.125 

0.125 

1.5 

1-5 

$0.0053 

$0.0638 

A 

i 

5-0 

I 

0.208 

0.208 

2-5 

2.5 

0.0088 

0.1059 

i 

5-0 

I 

0.25 

0.25 

3-o 

3-0 

0.0105 

O.I266 

i 

7-5 

IT5* 

0.291 

0.275 

3-5 

3-3 

O.OI2I 

0.1451 

i^ 

7-5 

IT5* 

0.366 

0.316 

4.4 

3-8 

O.OI47 

0.1762 

" 

2 

7-5 

0-5 

0.333 

6.0 

4.0 

0.0183 

O.22OO 

' 

2* 

IO.O 

2 

0.65 

0.366 

7-8 

4-5 

0.0226 

0.2719 

3 

IO.O 

2 

0.8 

0.416 

9-6 

5-0 

0.0273 

0.3274 

3* 

IO.O 

2 

I.O 

0-5 

I2.O 

6.0 

0.0337 

0.4050 

i 

4 

15.0 

3 

1-33 

0.633 

16.0 

7.6 

0.0443 

0.5320 

< 

4i 

15-0 

3  ' 

1.63 

0.775 

19.5 

9-3 

0.0593 

0.7II7 

1 

5 

15.0 

3 

1.88 

0.833 

22.6 

9.8 

0.06  1  6 

0.7388 

; 

1 

. 

si 

15.0 

3 

2.08 

0.875 

25.0 

10.5 

0.0673 

0.8077 

i 

4 

6 

15.0 

3 

2.29 

0.926 

27-5 

ii 

.2 

0.0734 

0.8814 

6| 

15.0 

3 

2.66 

I.O 

32.0 

I2.O 

0.084 

I.O 

7 

24.0 

4T8* 

3.13 

1.25 

37.6 

15.0 

O.IO 

1.  2O 

8 

25.0 

5  . 

3-33 

1.41 

40.0 

17.0 

0.1079 

1.295 

9 

26.0 

4.16 

1.66 

50.0 

2O.O 

0.1330 

1.5966 

j 

12 

28.0 

sV* 

7.0 

2.5 

84.0 

30.0 

0.175 

2.IO 

i 

15 

30.0 

6 

8.16 

4-5 

98.0 

54-0 

0.2827 

3407 

i 

23 

35-0 

7 

19-5 

6.0 

234.0 

72.0 

0.5925 

7.II 

1 

Cutting  with  Hand  Torch 

Cost  of  Gases, 

Thick- 

Time 

Gas  Consumption  in  Cubic  Feet 

Oxygen  at  2j  cents, 
Hydrogen  at  ij  cent 

ness, 
Inches 

Seconds 

Minutes 

Per  Lineal  Inch, 
Cut 

Per  Lineal  Foot, 
Cut 

Per  Lineal 

Per  Lineal 

Inch 

Foot 

Inch 

Foot 

Oxy. 

Hyd. 

Oxy. 

Hyd. 

A 

6.0 

IT2* 

0.23 

0.24 

2.76 

2.88 

$0.0099 

$0.1194 

i 

6.0 

IT% 

0.24 

0.24 

2.88 

2.88 

O.OIO2 

0.1224 

i 

6-5 

!TS* 

0-35 

0.32 

4.2 

3-84 

0.0143 

0.1722 

is 

7.5 

!t* 

0.40 

0-34 

4-8 

4.08 

0.0159 

0.1914 

2 

8.0 

JT* 

0.56 

0-44 

6.72 

5-28 

0.0217 

0.2604 

2\ 

8.5 

ly'fl 

0.76 

0.52 

9.12 

6.24 

0.0281 

0.3372 

3, 

9-5 

if9* 

1.04 

0.72 

12.48 

8.64 

0.0386 

0.4632 

3* 

I2.O 

2i45 

1.2 

0.9 

14.4 

10.8 

0.0457 

0.549 

4 

15.0 

3* 

i-55 

1.05 

18.6 

12.6 

0.0571 

0.6854 

4i 

17.0 

3T4* 

1.9 

i.iS 

22.8 

13-8 

0.0676 

0.8112 

5, 

20.0 

4 

2.4 

28.8 

15-6 

0.0827 

0.993 

si 

22.0 

4r4* 

2.6 

i-5 

31-2 

18.0 

0.0912 

1.095 

6 

23-5 

4rV 

2.8 

1.65 

33-6 

19.1 

0.0989 

1.186 

61 

25.0 

5 

3.1 

1.8 

37-2 

21.6 

0.109 

1.30 

7 

28.0 

ST% 

3-73 

1-95 

44.7 

23-4 

0.1342 

1.61 

8 

30.0 

6 

4.0 

2.1 

48.0 

32.4 

0.137 

1.644 

278  CUTTING   WITH  OXIDIZING  FLAME 

cutting  machine.  The  variation,  of  course,  depends,  to  some 
extent,  upon  the  -skill  of  the  operator. 

When  cutting  with  the  oxy-hydrogen  flame  and  assuming 
the  cost  of  oxygen  at  3  cents  per  cubic  foot,  and  the  cost  of  hydro- 
gen at  if  cent  per  cubic  foot,  the  cost  of  the  gas  per  foot  for 
cutting  J-inch  thick  steel  is  about  7  cents  and  the  cost  of  cutting 
i^-inch  thick  steel,  about  18  cents  per  lineal  foot.  Cutting 
with  a  hand  torch  increases  the  cost  slightly.  While  the  oxy- 
hydrogen  process  is  thus  more  expensive  than  the  oxy-acetylene 
process  for  thin  stock,  it  has  the  advantage  that  it  can  be  used 
on  much  heavier  material  than  the  oxy-acetylene  flame,  as 
explained  in  a  previous  paragraph. 

Difficulty  of  Making  Accurate  Cost  Estimates.  —  In  view  of 
such  difficulties  as  blow-holes  in  steel  castings,  scale  on  sheets, 
etc.,  it  is  generally  unsafe  for  a  welding  shop  to  make  a  flat  or 
contract  price  on  any  cutting  job,  even  after  an  inspection  of 
the  work  to  be  done.  A  better  plan  is  to  cover  the  labor  charge 
and  overhead  expenses,  profit,  etc.,  by  an  hourly  rate,  and  make 
a  reasonable  charge  for  the  gases  used.  The  gas  consumption 
cannot  be  determined  except  by  separating  the  gases  used  by 
the  heating  and  auxiliary  jets,  respectively.  A  fairly  accurate 
figure  for  the  gases  used  by  the  heating  jets  can  be  obtained  from 
the  manufacturers  of  the  torch,  but  the  oxygen  used  in  the  auxil- 
iary jet  will  vary  so  much,  due  to  the  opening  and  dosing  of  the 
valve  and  the  change  of  pressure  necessary  for  the  requirements 
of  the  case,  that  it  is  impossible  to  do  any  more  than  guess  at 
the  amount  consumed,  by  reading  the  gage  on  the  oxygen  tank. 
Of  course,  in  the  case  of  a  long  job,  the  total  amount  of  oxygen 
can  be  obtained  quite  accurately  from  the  number  of  tanks 
used,  but  this  cannot  be  used  as  a  basis  for  other  jobs  without 
considerable  risk. 

Increasing  the  Efficiency  of  the  Cutting  Torch.  —  Experi- 
ments recently  conducted  in  cutting  with  oxy-hydrogen  and 
oxy-acetylene  cutting  torches  show  that  a  marked  increase  in  the 
rate  of  production  is  effected  by  increasing  the  temperature  of 
the  oxygen.  The  most  favorable  results  secured  in  this  connec- 
tion show  that  the  increase  of  speed  obtained  by  preheating 


CUTTING  WITH  OXIDIZING  FLAME  279 

the  oxygen  is  18  per  cent,  while  the  saving  in  the  amount  of  oxy- 
gen used  is  55  per  cent.  As  an  increase  in  temperature  means 
a  corresponding  increase  in  the  pressure  of  the  oxygen,  it  seemed 
possible  that  merely  increasing  the  pressure  would  have  the  same 
effect.  Experiments  along  this  line  proved  that  this  reasoning 
was  correct.  Where  the  pressure  was  steadily  increased,  it  was 
found  that  the  rate  of  cutting  increased  in  direct  proportion. 
It  was  found,  however,  that  the  higher  pressures  had  a  tendency 
to  round  the  upper  edge  of  the  cut.  A  pressure  of  35.5  pounds 
per  square  inch  seems  to  be  about  the  maximum  amount  with 
which  perfect  work  could  be  produced.  With  very  low  pressures, 
the  rate  of  cutting  was  not  only  very  slow,  but  the  cut  itself  was 
defective.  Experiments  were  also  tried  in  changing  the  ratio 
of  hydrogen  to  oxygen,  and  it  was  found  that,  where  this  ratio 
was  15  to  4  instead  of  the  customary  4  to  i,  the  rate  of  cutting 
was  exceptionally  high  in  cases  where  the  pressure  of  the  oxygen 
was  about  the  maximum  of  35.5  pounds  per  square  inch. 


INDEX 


ACETONE  for  storing  acetylene,  37 
Acetylene,  35 
acetone  for  storing,  37 
compressed,  50 
Acetylene  generator,  37,  39 

British  type,  45 

design  of,  41 

portable,  44 

precautions  in  the  use  of,  38 
Acetylene  piping,  49 
Acetylene  tanks,  50 
Adjusting  the  welding  torch,  21 
Alignment  of  work  for  welding,  69,  161 
Alloys,  aluminum,  98 

aluminum-zinc,  welding,  193 

copper,  fluxes  for,  92 

copper,  welding,  179,  181 

copper,  welding-rods  for,  86 
Alloy  steels,  heat-treatment,  172 

welds  in,  85 
Aluminum,  184 

cleaning,  for  welding,  93 

flux  for,  92,  94,  184 

preheating  in  welding,  187 

welding,  184 

welding,  examples  of,  193,  197 

welding,  field  of,  196 

welding,  general  requirements,  191 

welding  material  for,  88 

welding  sheet,  189,  216 

welding  without  a  flux,  95,  185 
Aluminum  alloys,  98 

feeding  rods  for,  194 

zinc,  welding,  193 

Aluminum  castings  for  repair  work,  210 
Aluminum   crankcase,    repairing,    200, 

205 

Aluminum  housing,  repairing,  201 
Aluminum  transmission  case,  repairing, 
202 


Application  of  oxy-acetylene  welding,  4 

Asbestos  paper,  60 

Autogenous  welding,  definition,  2 

BABBITT  BEARINGS,  cooling  de- 
vice for,  57 

in  welding,  saving,  158 
Back-firing,  difficulty  due  to,  6 
Bars  and  mandrels,  rack  for,  56 
Bearings,  cooling  device  for  babbitt,  57 

saving  babbitt,  when  welding,  158 
Bench  for  welding,  57 
Beveling  edges  of  work  to  be  welded,  65 
Beveling,  welding  without,  67 
Blau-gas  for  welding,  49 
Blow-holes,  filling,  183 
Boiler  casting,  welding  a  heating,  138 
Boiler  welding,  217 

repairs,  219 

three-license  system,  218 
Brass,  filling  blow-holes  in,  183 

flux  for,  92 

strength  of  welds  in,  255 

welding,  182 

Brazing,  application  of,  I 
Bronze,  flux  for,  92 

manganese,  as  a  welding  material,  87 

strength  of  welds  in,  255 

Tobin,  as  a  welding  material,  87 

welding,  182 

CALCIUM   CARBIDE,   impurities 

in,  39 

Carbon,  influence  of,  on  welding,  163 
Casehardening  by  oxy-acetylene  flame, 

256 
Castings,  aluminum,  for  repair  work, 

210 
brass  or  copper,  filling  blow-holes  in, 

183 


281 


282 


INDEX 


Castings,  distortion  in  welding,  144 

production  of  malleable,  1 76 

repairing  cylinder,  129 

steel,  welding,  175 

steel,  welding  material  for,  86 

welding  heating  boiler,  138 
Cast-iron  crankcase,  welding,  119 

cutting,  270 

expansion  and  contraction,  155 

flux  for,  89 

welding,  in 

welding-rod  for,  83 

welding  to  steel,  175 

white,  163 

wrought  iron,  and  steel,  difference 

between,  164 
Cast-iron  welds,  defects  in,  116 

difficulties  with,  150 

example  of,  117 

finishing,  113 

strength  of,  251 

testing,  113 

C-clamps  for  welding,  58 
Charcoal  for  preheating,  73 
Chloride-of-potash  process  for  produc- 
ing oxygen,  24,  25 
City  gas  for  welding,  49 
Cleaning  aluminum  work,  93 
Cleaning  work  to  be  cut  by  flame,  267 
Composition  of  aluminum  fluxes,  94 
Compressed  acetylene,  50 
Contraction  and  expansion  of  cast  iron, 

155 
Cooling  device    for    babbitt   bearings, 

57 

Cooling  torch  tips,  22,  245 
Copper,  179,  181 

castings,  filling  blow-holes  in,  183 

flux  for,  91 

sheets,  216 

welding,  precautions  in,  180 

welding-rods  for,  86 

welding  to  steel,  181 
Copper  alloys,  fluxes  for,  92 

welding,  179,  181 

welding-rods  for,  86 
Cost  of  cutting  metals,  276 
Cost,  overhead,  in  welding,  246 


Cracking  or  warping,  69 
Crankcase,  repairing  aluminum,  200 

replacing  aluminum  lugs,  199 

welding  cast-iron,  119 
Crystalline  structure  of  iron  and  steel, 

164 
Cutting  metals,  cost  of,  276 

example  of,  275 

procedure  in,  268 

under  water,  275 

with  oxidizing  flame,  266 
Cutting  torches,  12,  266 

application  of,  272 

British  type,  17 

operation  of,  269 
Cylinders,  broken  walls,  126 

castings,  repairing,  129 

defective  welding  of,  135 

distortion  in  welding,  153 

flanges,  broken,  128 

preheating,  130 

properly  welded,  136 

repairing,  125 

Cylindrical  vessels,  welding  tops  and 
bottoms  to,  230 

DEFECTIVE  welding  of  cylinders,  135 

Defects  in  cast-iron  welds,  116 
Design  of  work  for  welding,  236 
Development    of    oxy-acetylene    weld- 
ing, 3 

Difficulties  with  cast-iron  welds,  150 
Distortion,  in  welding  cylinders,  153 

of  castings  in  welding,  144 
Drum,  rope,  preheating,  81 
Ductility  of  steel  welds,  253 

EDGES  of  work  to  be  welded,  bevel- 
ing* 65 
Electric,  welding,  used  in  conjunction 

with  oxy-acetylene  welding,  238 
Electrolytic  process  for  producing  oxy- 
gen, 24,  30 

Equal-pressure  welding  torch,  8 
Equipment,  for  oxy-acetylene  welding, 

6 

for  welding  shops,  machine  tool,  51 
miscellaneous,  for  welding  shops,  52 


INDEX 


283 


Expansion  and  contraction  of  cast  iron, 

155 

Expansion  pipe,  welded,  237 
Eye  protection,  64 , 

FEEDING-RODS      for      aluminum 

alloys,  194 

Filling  blow-holes,  183 
Fire  risk,  63 

Fittings,  welding  pipe,  67 
Flame,  for  welding  aluminum,  187 

neutral,  importance  of,  108,  no,  170 

oxy-acetylene,  107 

temperatures,  22 
Flanges,  cylinder,  broken,  128 
Floors  for  welding  shops,  52 
Flux,  welding  aluminum  without,  95, 

185 
Fluxes  used  for  welding,  83,  89,  101 

aluminum,  92,  184 

aluminum,  composition  of,  94 

brass,  92 

bronze,  92 

cast  iron,  89 

copper,  91 

copper  alloys,  92 

result  of  using  too  much,  in  welding 
aluminum,  185 

steel,  90 

wrought  iron,  90 
Forge  welding,  application  of,  i 
Forgings,  strength  of  welded,  250 
Frame,  preheating  press,  146 

repairing  a  machine,  117 

repairing  a  press,  145 
Furnace    for    preheating,     temporary, 

75 
Fusion  welding,  definition,  2 

GAGES  for  gas  pressures,  19 

Galvanized  plates,  welding,  222 
Gas,  city,  for  welding,  49 
Gases,  miscellaneous,  for  welding,  49 

used  for  cutting,  271 
Gas  pipe,  welding,  227 
Generators,  acetylene,  British  type,  45 

acetylene,  design  of,  41 

acetylene,  portable,  44 


Generators,  acetylene,  precautions  in 

the  use  of  38 
acetylene,  types  of,  37,  39 
hydrogen,  operation  of,  262,  263 
Graphite  mixture  for  use  in  welding, 
58 

HANDLING  heavy  hot  pieces,  68 
Hardening,  local,  by  oxy-acetylene 

flame,  256 

Hard  spots  in  cast-iron  welds,   150 
Heater  sections,  difficulty  in  welding, 

140 

Heating-boiler  casting,  welding,  138 
Heat-treatment,  of  alloy  steels,  172 
of  welded  steel,  170 
temperatures,  171 
High-carbon  steel,  cutting,  270 
High-speed    steel    to    machine    steel, 

welding,  174 

Hoists  for  welding  shops,  52 
Homogeneous  welding,  definition,  2 
Hood  used  for  preheating,  76 
Household  utensils,  welding,  233 
Housing,  repairing  aluminum,  201 
Hydraulic  safety  valves,  19 
Hydrogen,  48 
Hydrogen  generators,  262 

IMPURITIES,  in  calcium  carbide,  39 

in  oxygen,  influence  of,  35 
Injector  type  torch,  8 
Iron  and  steel,  crystalline  structure,  164 

difference  between,  164 
Iron,  cast,  cutting,  270 

expansion  and  contraction,  155 

flux  for,  89 

welding  of,  in 
Iron,  malleable,  constitution  of,  99 

cutting,  270 

material  for  welding,  88 

welding,  175 

Iron,  metallurgy  of,  and  its  relation  to 
welding,  162 

Swedish    or    Norway,    for    welding 
steel,  84 

white  cast,  163 
Iron,  wrought,  flux  for,  90 


284 


INDEX 


JACKETS,  water,  broken  by  freezing, 

125 

Jigs  and  V-blocks  for  welding,  55 
Joints,  for  household  utensils,  234 
for  sheet-metal  vessels,  228 

LEAD  burning,  257 
apparatus  used  for,  261 
outfits,  265 

Lead,  starting  a  weld,  260 
Liquid-air  process  for  producing  oxygen, 

23,  26 
Local  hardening  by  oxy-acetylene  flame, 

256 
Low-pressure  torches,  9 

MACHINE  for  welding  tubes,  225 

Machine  frame,  repairing,  117 
Machine  steel  to  high-speed  steel,  weld- 
ing, 174 
Machine  tool  equipment  for   welding 

shops,  51 
Malleable  iron,  black-heart,  88 

castings,  production  of,  176 

constitution  of,  99 

cutting,  270 

material  for  welding,  88 

procedure  in  welding,  177 

welding,  175 

white-heart,  88 
Mandrels,  rack  for,  56 
Manganese-bronze   as   a   welding   ma- 
terial, 87 

Manifolds,  repairing  aluminum,  198 
Materials  used  for  welding,  83 
Medium-pressure  torches,  8,  n 
Metal  cutting,  cost  of,  276 

example  of,  275 

under  water,  275 

with  oxidizing  flame,  266 
Metallurgy  of  iron  and  its  relation  to 
welding,  162 

NEUTRAL  flame,  108,  no 

importance  of,  170 
Non-ferrous  metals,  strength  of  welds, 

255  ^ 
Norway  iron  wire  for  welding  steel,  84 


OVERHEAD  cost  in  welding,  246 
Oxy-acetylene  flame,  107 
temperature,  22 
thickness  of  metal  cut  by,  269 
Oxy-acetylene  welding,  103 

apparatus,  22 

application  of,  4 

cast  iron,  in 

development  of,  3 

equipment,  6 

fluxes  for,  89 

general  considerations,  239 

principle,  3 

Oxygen,  chloride-of-potash  process,  24, 
25 

electrolytic  process,  24,  30 

influence  of  impurities  in,  35 

in  tanks,  25,  50 

liquid-air  process,  23,  26 

methods  for  producing,  23 

piping,  49 

temperature  of,  for  cutting,  271 

welding  regulators,  19 
Oxy-hydrogen  flame,  temperature,  22 

thickness  of  metal  cut  by,  269 

PATTERNS,  plaster-of-paris,  60 
Phosphorus,    influence,    in    welding 
copper,  91 

in  welding-rod,  180 
Pintsch  gas  for  welding,  49 
Pipe  fittings,  welding,  67 
Piping,  for  gases,  49 

manufacture  by  oxy-acetylene  weld- 
ing, 223 

welded  expansion,  237 

welded,  tests  on,  226 

welding  gas,  227 
Plaster-of-paris  patterns,  60 
Plate,  tin,  welding,  223 

welding  galvanized,  222 

welding,  speed  of,  215 
Portable  acetylene  generators,  44 
Precautions,  safety,  in  welding,  249 
Preheating,  72 

charcoal  for,  73 

cylinders,  130 

examples  of,  80 


INDEX 


285 


Preheating,  heater  sections,  142 

hood  used  for,  76 

in  welding  aluminum,  187 

miscellaneous  means  for,  73 

object  of,  74 

press  frame,  146 

rope  drum,  81 

temperatures,  77 

temporary  furnace  for,  75 
Preparation  of  work  for  welding,  65 
Press  frame,  preheating,  146 

repairing,  145 
Press  repair,  punch,  161 
Puddling  rod  for  welding  aluminum,  186 
Punch-press  repair,  161 

RACK  for  bars  and  mandrels,  56 

Refractory  graphite  mixture,  58 
Regulating  valves,  18 
Repairing,   aluminum   crankcase,    200, 
205 

aluminum  housing,  201 

aluminum  transmission  case,  202 

cylinder  casting,  129 

cylinders  by  welding,  125 

machine  frame,  117 

press  frame,  145 

punch-press,  161 
Rest   periods  required  on  large  work, 

245 

Retorts,  welding,  228 
Rocker  arm,  welding  a  shaper,  122 
Rope  drum,  preheating,  81 

SAFTY  precautions  in  welding,  249 

Safety  valves,  hydraulic,  19 
Setting-up  work  for  welding,  71 
Shaper  rocker  arm,  welding,  122 
Sheet-metal  vessels,  welding,  228 
Sheets,  aluminum,  welding,  189,  216 

boiler,  welding,  217 

copper,  welding,  216 

metal,  welding,  212 

steel,  welding  thin,  213 

tin,  welding,  223 

welding  galvanized,  222 

welding,  speed  of,  215 
Soldering,  application  of,  i 


Speed  of  sheet  and  plate  welding,  215 
Spots,  hard,  in  cast-iron  welds,  150 

in  welding,  175 

Spring  steel,  welding-wire  for,  85 
Steel,  alloy,  welding,  85 

burning,  166 

castings,  welding,  175 

castings,  welding  material  for,  86 

cast  iron,  and  wrought  iron,  differ- 
ence between,  164 

crystalline  structure,  164 

flux  for,  90 

heat-treatment  of  alloy,  172 

heat-treatment  of  welded,  170 

high-carbon,  cutting,  270 

kinds  generally  welded,  166 

methods  for  welding,  168 

sheet,  welding  thin,  213 

spring,  welding- wire  for,  85 

tool,  welding  material  for,  86 

torch  tip  for  welding,  170 

welding,  general  procedure,  162 

welding  high-speed  to  machine,  174 

welding  to  cast  iron,  175 

welding  to  copper,  181 

welding-wire  for,  84 

welds,  ductility  of,  253 

welds,  strength  of,  251 
Strength  of  welds,  in  forgings,  250 

in  non-ferrous  metals,  255 

tests  on,  251 
Swedish  iron  wire  for  welding  steel,  84 

TABLE  for  welding,  54 

Tanks,  acetylene  and  oxygen,  50 
for  oxygen,  25 
welding,  228 
welding  heads  of,  217 
Temperature,  for  heat-treatment,   171 
of  oxy-acetylene  flame,  22 
of  oxygen  for  cutting,  271 
of  oxy- hydrogen  flame,  22 
preheating,  77 

Tests,  on  cast-iron  welds,  113 
on  strength  of  welds,  251 
on  welded  tubing,  226 
Thickness  of  metal  that  can  be  cut  by 
oxy-acetylene  flame,  269 


286 


INDEX 


Thickness  of  metal  that  can  be  cut  by 

oxy-hydrogen  flame,  269 
Tin  plate  welding,  223 
Tips  of  torch,  care  of,  22 

cooling,  245 

for  welding  steel,  170 

size  of,  21 

Tobin  bronze  as  a  welding  material,  87 
Tool  steel,  welding  material  for,  86 
Torches,  commercial  designs,  n 

cutting,  12,  266 

cutting,  application  of,  272 

cutting,  British  type,  17 

cutting,  operation  of,  269 

equal-pressure  welding,  8 

for  different  purposes,  15 

injector  type,  8 

low-pressure,  9 

manipulating,  in  welding  aluminum, 
188 

medium-pressure,  8,  n 

welding,  6 

welding,  adjusting,  21 

welding,  requirements  of,  7 

welding,  types  of,  8 
Torch  tips,  care  of,  22 

cooling,  245 

for  welding  steel,  170 

size  of,  21 

Training  of  welders,  243 
Transmission  case,  repairing  aluminum, 

202 

Tube  welding  machine,  225 
Tubing,  manufacture  by  oxy-acetylene 
welding,  223 

welded,  tests  on,  226 

UTENSILS,  welding,  233 

VALVES,  hydraulic  safety,  19 

regulating,  18 

V-blocks  and  jigs  for  welding,  55 
Vises  for  welding,  57 

\VAGES  of  welders,  244 

Walls  of  cylinders,  broken,  126 
Warping  in  sheet-metal  welding,  212 
Warping  or  cracking,  69 


Water  jackets  broken  by  freezing,  125 
Welders,  on  repair  work,  243 

qualifications  of,  240 

training  of,  243 

wages  of,  244 
Welding,  alloy  steels,  85 

aluminum,  184 

aluminum,  examples  of,  193,  197 

aluminum,  field  of,  196 

aluminum,  flux,  184 

aluminum,  general  requirements,  191 

aluminum  sheets,  216 

aluminum  without  a  flux,  95,  185 

aluminum-zinc  alloys,  193 

apparatus,  22 

application  of  oxy-acetylene,  4 

autogenous,  definition,  2 

boilers,  217 

brass,  182 

broken  cylinders,  125 

bronze,  182 

cast  iron,  1 1 1 

cast-iron  crankcase,  119 

cast  iron  to  steel,  175 

copper,  179,  181 

copper  alloys,  179,  181 

copper  sheets,  216 

copper  to  steel,  181 

cylinders,  distortion  in,  153 

development  of  oxy-acetylene,  3 

distortion  of  castings  in,  144 

electric,    used    in    conjunction    with 
oxy-acetylene  welding,  238 

equipment,  6 

fluxes  for,  83,  89,  101 

forge,  application  of,  i 

fusion,  definition,  2 

galvanized  plates,  222 

gas  pipe,  227 

general  considerations,  239 

general  precautions  in  cast-iron,  115 

general  rules  for,  104 

heads  of  tanks,  217 

heating-boiler  casting,  138 

high-speed  steel  to  machine  steel,  1 74 

homogeneous,  definition,  2 

household  utensils,  233 

machine  tube,  225 


INDEX 


287 


Welding,  malleable  iron,  175 
materials  and  fluxes  used  for,  83 
miscellaneous  gases  for,  49 
oxy-acetylene,     commercial     limita- 
tions, 248 

oxy-acetylene,  principle,  3 
pipe  fittings,  67 
preparation  of  work  for,  65 
press  frame,  146 
regulators,  19 
rods,  83 

safety  precautions,  249 
setting-up  work  for,  71 
shaper  rocker  arm,  122 
sheet  aluminum,  189 
sheet  metal,  212 
shops,  arrangement,  62 


Welding,    shops,  machine   tool  equip- 
ment, 51 

speed  of  sheet  and  plate,  215 

spots  in,  175 

steel  castings,  175 

steel,  methods  for,  162,  168 

table  for,  54 

tin  plate,  223 

torches,  6 

unusual  difficulties,  239 

wire  for  steel,  84 

with  city  gas,  49 

without  beveling,  67 
White  iron,  163 

Wrought    iron,    cast    iron,    and    steel, 
difference  between,  164 

flux  for,  90 


THIS  BOOK  IS  DUE  ON  THE  LAST  BATE 
STAMPED  BELOW 


AN     INITIAL    FINE     OF     25     CENTS 

WILL.  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


DEC    7    192 


°fC     9   , 


''932 


35 


MAY    131336 
F£B  24  7937 


194G 


LD  21-50m-8,'32 


358844 


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